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EP2720817B1 - Method for forming channels in a tool and computer program product that performs such a method - Google Patents

Method for forming channels in a tool and computer program product that performs such a method Download PDF

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Publication number
EP2720817B1
EP2720817B1 EP12731553.9A EP12731553A EP2720817B1 EP 2720817 B1 EP2720817 B1 EP 2720817B1 EP 12731553 A EP12731553 A EP 12731553A EP 2720817 B1 EP2720817 B1 EP 2720817B1
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EP
European Patent Office
Prior art keywords
tooling
heat transfer
temperatures
temperature
transfer fluid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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EP12731553.9A
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German (de)
French (fr)
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EP2720817A2 (en
Inventor
Alban AGAZZI
Yvon Jarny
Ronan LE GOFF
David Garcia
Vincent SOBOTKA
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pole Europeen De Plasturgie
Universite de Nantes
Original Assignee
Pole Europeen De Plasturgie
Universite de Nantes
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Publication of EP2720817A2 publication Critical patent/EP2720817A2/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/20—Accessories: Details
    • B22D17/2015—Means for forcing the molten metal into the die
    • B22D17/2038—Heating, cooling or lubricating the injection unit

Definitions

  • the present invention relates to a method for forming thermal control channels in a tool for molding plastic or metal parts.
  • the present invention relates to a method in which the shape of the thermal control channels is defined.
  • the present invention relates to a tool for molding plastic or metal parts, in which thermal control channels are formed by implementing such a method.
  • the present invention relates to a computer program product implementing an algorithm performing such a method.
  • the present invention finds particular application in the field of design and manufacture of tools for molding which include thermal control channels.
  • the present invention may find application in the fields of injection molding, rotational molding or heat blasting.
  • the present invention can be implemented to shape a plastic material or a metallic material.
  • a molding cycle of a part consists in particular possibly preheating the tool, to introduce the material in the tool, to cool the part, then to unmold the piece out of the tooling.
  • the thermal control channels have the particular function of regulating the temperature of the tool, for example by preheating it before the introduction of the material into the molding cavity of the tool.
  • the thermal control channels also have the function of cooling the part before its demolding out of the tooling. This cooling and this possible preheating affect the duration of the manufacturing cycle of each part and the manufacturing quality of each part, so the rate of defective parts.
  • the manufacturing defects observed on the defective parts are, for example, a deviation from the nominal dimension of the part, a lack of material, etc.
  • the thermal control channels are formed or designed after defining the general shape of the tool, in particular its molding cavity.
  • the dimensions of the thermal control channels and their positions in a tool of the prior art are, in whole or in part, determined empirically by a man of the art. For this purpose, one skilled in the art takes particular account of the geometry of the part, the material to be injected and the recommendations of the manufacturer of the material for molding.
  • thermal control channels may perform imperfectly because the channel dimensions and positions and the molding process parameters are not optimal. Thus, such thermal control channels may induce a relatively long cycle time to properly cool each piece and / or a relatively low manufacturing quality, so a rate of relatively large defective parts.
  • the present invention aims to solve, in whole or in part, the problems mentioned above.
  • the thermal control channels are defined, in position and in size, by simulating the temporal variation of the temperatures induced in the tooling in the vicinity of the workpiece by the amounts of heat exchanged between workpiece and tooling.
  • the position and size of a thermal control channel are then determined by the stationary zones and the isothermal surfaces.
  • the parameters of the molding process such as the temperature of a heat transfer fluid and the duration of a molding cycle, can be determined from the selected isothermal surfaces.
  • such a method of forming these channels makes it possible to optimize the thermal regulation of the tooling, thus to effectively regulate the tooling in temperature and to obtain uniform temperatures on the surface of the workpiece and in the volume of the workpiece. part during the cooling of the part and / or during a preheating of the tooling. The duration of a cycle and / or the rate of defective parts can therefore be reduced and the manufacturing quality of each part can be increased.
  • channel designates a cavity which is made in the material of the tool and which is supplied with heat transfer fluid by at least one thermoregulator circuit.
  • thermal field denotes a tensor associating a simulated temperature level with each spatial and temporal coordinate of a point of the reference volume.
  • the step of "selecting an isothermal surface to define at least a portion of a peripheral surface of a thermal control channel” does not necessarily imply that this peripheral surface portion is defined strictly coincides with the selected isothermal surface.
  • the definition of a thermal control channel also incorporates machining constraints, which vary according to the machining mode of the channel.
  • drilling does not make it possible to produce a channel of complex shape, in particular a curve; in this case, the channel will be defined or drawn roughly by “leaning" on the isothermal surface.
  • a generative process such as laser fusion, allows to build a channel of very complex shape; in this case, the channel can be defined or drawn almost identically to the selected isothermal surface.
  • coolant means a fluid whose function is to transport heat between two or more sources having different temperatures, that is to say to bring or remove a quantity of heat to a solid element.
  • heat transfer fluid is equivalent to "thermal control fluid”.
  • the reference volume comprises all or part of the part plus an intermediate volume extending between the outer surface of the workpiece and a reference surface, which is located in the tooling, therefore outside the workpiece .
  • the step of determining the thermal field comprises a calculation based on said temperature distribution on the reference surface.
  • Such an expansion makes it possible to define the reference surface.
  • Such an erosion makes it possible to define a fictitious surface delimiting the solid phase or solid sheath and the molten phase of the material introduced into the tooling.
  • the morphological erosion is carried out by means of a structuring element, for example a sphere, a dimension of which is substantially equal to a predetermined thickness of a solid sheath of the workpiece for demolding the workpiece. .
  • a structuring element for example a sphere, a dimension of which is substantially equal to a predetermined thickness of a solid sheath of the workpiece for demolding the workpiece.
  • the morphological dilation is carried out by means of a structuring element, for example a sphere, a dimension of which is greater than a predetermined distance to ensure the mechanical strength of the tooling after formation of the thermal regulation channels.
  • a structuring element for example a sphere, a dimension of which is greater than a predetermined distance to ensure the mechanical strength of the tooling after formation of the thermal regulation channels.
  • the method further comprises a subsequent step of completely forming a peripheral surface a respective thermal control channel by closing said peripheral surface portion when said peripheral surface portion is partially delimited by the reference surface.
  • a thermal regulation channel can be completely defined throughout its surface.
  • a respective heat transfer fluid temperature is associated with each thermal control channel, when the isothermal surfaces selected respectively within distinct quasi- stationary regions correspond to different temperatures.
  • the number of different heat transfer fluid temperatures that are associated with the thermal control channels is limited to the number of thermoregulatory circuits for supplying heat transfer fluid heat transfer channels.
  • thermoregulatory circuits as selected isotherms.
  • the shape of a respective thermal regulation channel is defined so as to minimize the pressure drops generated during the flows of the coolant.
  • each isothermal surface is selected within a respective quasi-stationary region so as to separate the thermal regulation channels and the outer surface of the part so that the tooling withstands the thermomechanical stresses likely to practice during the manufacture of a piece.
  • each isothermal surface is selected within a respective quasi-stationary region so that, between the moment of introduction of the material into the tool and the moment of demolding of the workpiece, the temperature of a respective isothermal surface is within a predetermined range depending on the material injected.
  • the temperature distribution of at least one coolant on the reference surface is determined by means of an optimization algorithm involving the so-called conjugated gradient method, preferably coupled with the so-called multiplier technique. of Lagrange.
  • the subject of the present invention is a tool intended to manufacture at least one part by molding a material, the tooling comprising heat regulation channels, the tool being characterized in that all or part of the control channels are formed by implementing a method according to the invention.
  • such tooling has optimized thermal regulation, to achieve effective thermal control and obtain uniform temperatures on and in the room during the cooling of the room.
  • the duration of a cycle and / or the rate of defective parts can therefore be reduced and the manufacturing quality of each part can be increased.
  • the subject of the present invention is a computer program product which implements an algorithm implementing a method according to the invention.
  • Such a computer program product makes it possible to automatically and optimally design the formation of cooling channels in the tooling, in particular from the geometry of the part, the material to be injected and the recommendations of the manufacturer of the machine. material for molding purposes.
  • the figure 1 illustrates a section 4, the molding of which is carried out according to a method according to the invention and by means of a tooling 2.3 according to the invention.
  • the tooling 2.3 is essentially composed of two tooling parts 2 and 3.
  • a "T" -shaped cross-section forms the base of the profile 4.
  • the tooling 2.3 is formed of two mold parts 2 and 3, which delimit a molding cavity.
  • the profile 4 has an outer surface 4.1.
  • the process illustrated by the Figures 1 to 6 comprises a step in which the temperatures resulting from heat transfers from the section 4 to the tooling 2.3 are simulated between the instant of introduction of the material in the tooling 2.3 and the moment of demolding of the profile 4 out of the molding cavity of the tool 2.3.
  • the process illustrated by the Figures 1 to 6 comprises a step in which the thermal field of the induced temperatures is determined in a reference volume 17.4 which comprises the profile 4 and the intermediate volume 17 which extends from the profile 4 to a reference surface 11 which is located in the tooling 2.3 .
  • the intermediate volume 17 corresponds to the volume of a portion of the tooling 2.3 which is close to the molding cavity where the thermoplastic material is to be injected.
  • the molding cavity of the tooling 2.3 corresponds to the external surface 4.1 of the profile 4.
  • the temperatures are induced by the transfers of heat that occur between the thermoplastic material injected to form the profile 4 and the tooling 2.3.
  • the "thermal field” is a tensor associating a simulated temperature level with each spatial and temporal coordinate of a point of the reference volume 17.4.
  • each isothermal surface 23 is materialized by a disjoint curved line of the adjacent isothermal surfaces 23.
  • the process illustrated by the Figures 1 to 6 comprises a step in which morphological expansion of the outer surface 4.1 of the profile 4 is carried out so as to define the reference surface 11, hereinafter referred to as the expanded surface 11.
  • Channels 1 fulfill a thermal regulation function. On the one hand, they channel the flow of a heat transfer fluid which is colder than the temperature of introduction of the material in the cavity or mold cavity of the tooling 2.3. Such a flow causes heat transfer between the section 4 and the coolant, which allows to cool the profile 4. On the other hand, if necessary, they channel the flow of a heat transfer fluid to preheat the tooling 2.3, which improves the quality of the molded profiles 4.
  • the structuring element guiding the morphological dilation is a first sphere, not shown, whose diameter is for example about 4 times the thickness of the profile.
  • the diameter of the sphere is greater than a predetermined distance to ensure the mechanical strength of the tooling 2.3 after formation of the thermal control channels 1. This distance is for example greater than about 3 mm, or even about 4 mm.
  • the process illustrated by Figures 1 to 6 comprises a step in which morphological erosion of the outer surface 4.1 of the profile 4 is performed so as to define an eroded surface 12.
  • the structuring element guiding the morphological erosion is a second sphere, not shown, a dimension of which is substantially equal to a predetermined thickness of a solid sheath of the profile 4 for the demolding of the profile 4.
  • the thickness of the solid sheath is predetermined in particular depending on the molded material and the geometry of the part, here the profile 4, so that the profile 4 has a mechanical resistance allowing its demolding without geometric alteration. After demolding, the portion of the section 4 which has not yet solidified continues to cool, then solidifies too. The profile 4 then has its final mechanical strength.
  • the expression "temperature distribution” designates a tensor associating a simulated temperature level with each spatial and temporal coordinate of a point of a surface, here of the reference surface 11.
  • This temperature distribution on the expanded surface 11 is obtained by simulating the heat transfer between the section 4, the tooling 2.3 and a heat transfer fluid for cooling.
  • This temperature distribution on the expanded surface 11 is determined by calculation by means of an optimization algorithm involving the so-called conjugate gradient method, preferably coupled with the so-called Lagrange multiplier technique.
  • the process illustrated in Figures 1 to 6 includes a calculation based on this temperature distribution on the dilated surface 11.
  • the hot spots of the intermediate volume 17 are represented by dashed zones sparse at the figure 4 and the cold points of the intermediate volume 17 are materialized by dashed areas dense with the figure 4 .
  • the process illustrated by the Figures 1 to 6 further comprises a step in which quasi-stationary regions 21 are located in the thermal field.
  • figure 4 each quasi-stationary region 21 is globally marked by an ellipse.
  • a quasi-stationary region 21 of the intermediate volume 17 is a region in which the displacement of at least one isothermal surface 23 during a reference period remains approximately constant. In other words, this displacement has an amplitude less than a predetermined displacement limit.
  • each isothermal surface 23 varies (nt), during a molding cycle, as a function of the heat transfer between the section 4 and the tooling 2.3.
  • the reference period is between the instant of introduction of the material into the tooling 2.3 and the moment of demolding of the profile 4.
  • the reference period corresponds to a complete molding cycle of a section 4.
  • the reference period comprises at least two distinct phases.
  • the first phase extends from the moment of introduction of the material into the tooling 2.3 until the moment of release of the profile 4.
  • the second phase extends from the moment of demolding of the previous section 4 until to a new introduction of material for molding the next profile.
  • a shorter reference period can be between the instant of introduction of the material in the tooling 2.3 and the moment of release of the profile 4.
  • the reference period is chosen so that it corresponds to the first phase of a complete molding cycle.
  • the process illustrated by the Figures 1 to 6 comprises a step in which an isothermal surface 23 is selected within each quasi-stationary region 21 to define portions 23.1, 23.2 and 23.3 of peripheral surfaces for the respective channels 1.
  • each portion 23.1, 23.2 or 23.3 is generally elliptical.
  • Portions 23.1, 23.2 and 23.3 correspond to isothermal surfaces 23 whose simulated temperature level is approximately 305 K (degrees Kelvin).
  • distinct portions may correspond to isothermal surfaces whose simulated temperature levels are distinct, for example respectively about 324 K, 330 K and 335 K (degrees Kelvin).
  • the method illustrated by the Figures 1 to 6 may further comprise a subsequent step of completely forming the respective peripheral surface of each channel 1 by closing each portion 23.1, 23.2 or 23.3. This closure is formed according to the method of making the channels 1.
  • the channels are closed by following relatively simple patterns. Such channels are illustrated in dashed lines at figure 6 With the reference 10. Since the channel pattern 10 differs from the selected isothermal surfaces 23, the thermal regulation is not quite optimal.
  • the channels are closed by following relatively complex patterns, which optimizes the thermal regulation.
  • Such channels are illustrated in solid lines at the figure 6 with the reference 1. Insofar as the pattern of the channels 1 matches the selected isothermal surfaces 23, the thermal regulation can be optimal.
  • each channel 1 is drawn in a rectilinear manner and perpendicular to the plane of the figure 6 .
  • Such a layout minimizes the pressure losses generated during the flows of the heat transfer fluid.
  • each channel 1 can also be traced in particular according to the opening kinematics of the tooling 2.3, that is to say the separation of the tooling parts 2 and 3 , and the position in the tooling 2.3 of thermoplastic supply ducts, usually called "carrots".
  • channels 1 or 10 the designer can thus achieve a balanced solution between the thermal regulation constraints and the other functions that the tooling 2.3 fulfills.
  • a respective heat transfer fluid temperature for example 330 K, may be associated with a respective channel 1, in the case where the isothermal surfaces 23 selected within distinct quasi-stationary regions 21 correspond to different temperatures.
  • a coolant temperature is associated with the channels 1.
  • the number of thermoregulatory circuits not shown for supplying heat transfer fluid to the channels 1 is at least one. In the alternative where several isotherms are selected, the number of thermoregulatory circuits for supplying the heat transfer fluid to the channels may be greater than one, for example equal to three.
  • each isothermal surface 23 is selected inside a respective quasi-stationary region 21 so as to separate each channel 1 and the outer surface 4.1 of the profile 4 so that the tooling 2.3 withstands the thermomechanical stresses likely to during the molding of the profiles 4.
  • a distance between a channel 1 and the outer surface 4.1 of the section 4 may be greater than 3 mm or even 4 mm.
  • the tooling 2.3 comprises channels 1 formed by implementing a method according to the invention.
  • the shapes of the channels 1 have been defined or calculated by implementing this method, and then the tooling 2.3 has been machined from the dimensions of these shapes of the channels 1.
  • FIGS 7 to 11 illustrate a method according to a second embodiment of the invention for forming channels 101 in a tool 102.103 according to a second embodiment of the invention.
  • the description of the tooling 2.3 and the corresponding method given above in relation to the Figures 1 to 6 can be transposed to the tool 102.103 and the corresponding method, with the notable exception of the differences set out below.
  • channels 101, tool 102.103 are defined with parts of molds 102 and 103, a workpiece 104 with an outer surface 104.1, an expanded surface 111, an eroded surface 112, an intermediate volume 117, a reference volume 117.104, quasi-stationary regions 121, isothermal surfaces 123, portions 123.1 and 123.2.
  • the piece 104 differs from the profile 4, because the piece 104 has the overall shape of a quarter box.
  • the tool 102.103 differs from the tool 2.3, because its molding cavity has generally the shape of a quarter parallelepiped.
  • the figure 8 illustrates the expanded surface 111 and the eroded surface 112, which also have specific shapes in relation to the piece 104.
  • the figure 8 also illustrates a supply conduit or core 107 for the injection of the thermoplastic material.
  • the quasi-stationary regions 121 are represented at the figure 10 .
  • the channels 101 are represented at figure 11 .
  • the quasi-stationary regions 121 and therefore the channel regions 101 have more complex shapes than the channels 1. For this reason, the channels 101 are to be machined by a generative method, such as selective sintering by laser.
  • Isothermal surfaces 123.1 and 123.2 corresponding to a temperature level is selected in the quasi-stationary regions 121.
  • the tool 102.103 comprises channels 101 formed by implementing a method according to the invention.
  • a computer program product which implements an algorithm implementing such a method.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Description

La présente invention concerne un procédé pour former des canaux de régulation thermique dans un outillage destiné au moulage de pièces en plastique ou en métal. En d'autres termes, la présente invention concerne un procédé dans lequel on définit la forme des canaux de régulation thermique. De plus, la présente invention concerne un outillage pour mouler des pièces en plastique ou en métal, dans lequel des canaux de régulation thermique sont formés en mettant en oeuvre un tel procédé. Par ailleurs, la présente invention concerne un produit programme d'ordinateur mettant en oeuvre un algorithme réalisant un tel procédé.The present invention relates to a method for forming thermal control channels in a tool for molding plastic or metal parts. In other words, the present invention relates to a method in which the shape of the thermal control channels is defined. In addition, the present invention relates to a tool for molding plastic or metal parts, in which thermal control channels are formed by implementing such a method. Furthermore, the present invention relates to a computer program product implementing an algorithm performing such a method.

La présente invention trouve notamment application dans le domaine de la conception et de la fabrication d'outillages pour le moulage qui comprennent des canaux de régulation thermique. La présente invention peut trouver application dans les domaines du moulage par injection, du rotomoulage ou du thermosoufflage. La présente invention peut être mise en oeuvre pour mettre en forme une matière plastique ou un matériau métallique.The present invention finds particular application in the field of design and manufacture of tools for molding which include thermal control channels. The present invention may find application in the fields of injection molding, rotational molding or heat blasting. The present invention can be implemented to shape a plastic material or a metallic material.

Un cycle de moulage d'une pièce consiste notamment à préchauffer éventuellement l'outillage, à introduire la matière dans l'outillage, à refroidir la pièce, puis à démouler la pièce hors de l'outillage. Les canaux de régulation thermique ont notamment pour fonction de réguler la température de l'outillage, par exemple en le préchauffant avant l'introduction de la matière dans la cavité moulante de l'outillage. Les canaux de régulation thermique ont aussi pour fonction de refroidir la pièce avant son démoulage hors de l'outillage. Ce refroidissement et cet éventuel préchauffage influent sur la durée du cycle de fabrication de chaque pièce et sur la qualité de fabrication de chaque pièce, donc sur le taux de pièces défectueuses. Les défauts de fabrication observés sur les pièces défectueuses sont par exemple un écart à la cote nominale de la pièce, un manque de matière etc.A molding cycle of a part consists in particular possibly preheating the tool, to introduce the material in the tool, to cool the part, then to unmold the piece out of the tooling. The thermal control channels have the particular function of regulating the temperature of the tool, for example by preheating it before the introduction of the material into the molding cavity of the tool. The thermal control channels also have the function of cooling the part before its demolding out of the tooling. This cooling and this possible preheating affect the duration of the manufacturing cycle of each part and the manufacturing quality of each part, so the rate of defective parts. The manufacturing defects observed on the defective parts are, for example, a deviation from the nominal dimension of the part, a lack of material, etc.

Dans l'art antérieur, les canaux de régulation thermique sont formés ou conçus après avoir défini la forme générale de l'outillage, en particulier de sa cavité moulante. Dans un procédé de l'art antérieur, les dimensions des canaux de régulation thermique et leurs positions dans un outillage de l'art antérieur sont, en tout ou partie, déterminées empiriquement par un homme de l'art. Dans ce but, l'homme de l'art tient notamment compte de la géométrie de la pièce, de la matière à injecter et des recommandations du fabricant de la matière en vue de son moulage.In the prior art, the thermal control channels are formed or designed after defining the general shape of the tool, in particular its molding cavity. In a method of the prior art, the dimensions of the thermal control channels and their positions in a tool of the prior art are, in whole or in part, determined empirically by a man of the art. For this purpose, one skilled in the art takes particular account of the geometry of the part, the material to be injected and the recommendations of the manufacturer of the material for molding.

Cependant, cette détermination empirique nécessite de réaliser de nombreux prototypes et de nombreux réglages pour former tout nouvel outillage, ce qui est long et coûteux. En outre, des canaux de régulation thermique formés empiriquement risquent de remplir leurs fonctions de manière imparfaite, car les dimensions et positions des canaux et les paramètres du procédé de moulage ne sont pas optimaux. Donc, de tels canaux de régulation thermique risquent d'induire une durée de cycle relativement longue pour refroidir convenablement chaque pièce et/ou une qualité de fabrication relativement faible, donc un taux de pièces défectueuses relativement important. La présente invention vise notamment à résoudre, en tout ou partie, les problèmes mentionnés ci-avant.However, this empirical determination requires many prototypes and adjustments to form all new tools, which is time consuming and expensive. In addition, empirically formed thermal control channels may perform imperfectly because the channel dimensions and positions and the molding process parameters are not optimal. Thus, such thermal control channels may induce a relatively long cycle time to properly cool each piece and / or a relatively low manufacturing quality, so a rate of relatively large defective parts. The present invention aims to solve, in whole or in part, the problems mentioned above.

A cet effet, l'invention a pour objet un procédé, pour former des canaux de régulation thermique dans un outillage destiné à fabriquer au moins une pièce par moulage d'une matière dans l'outillage, puis par refroidissement de la pièce au moyen d'au moins un fluide caloporteur circulant dans des canaux de régulation thermique jusqu'à une température de démoulage prédéterminée, puis par démoulage de la pièce hors de l'outillage, le procédé comprenant les étapes :

  • simuler les températures qui sont induites par des transferts de chaleur entre la pièce et l'outillage et entre un instant d'introduction de la matière dans l'outillage et l'instant de démoulage de la pièce ;
  • déterminer un champ thermique des températures induites dans un volume de référence comprenant la pièce et un volume intermédiaire s'étendant entre la surface externe de la pièce une surface de référence située dans l'outillage ;
  • localiser dans le champ thermique des régions dites quasi-stationnaires, dans chacune desquelles le déplacement d'au moins une surface isotherme durant une période de référence présente une amplitude inférieure à une limite de déplacement prédéterminée, ladite période de référence étant comprise entre l'instant d'introduction de la matière dans l'outillage et l'instant de démoulage de la pièce ; et
  • à l'intérieur de chaque région quasi-stationnaire, sélectionner une surface isotherme pour définir au moins une portion d'une surface périphérique d'un canal de régulation thermique respectif.
For this purpose, the subject of the invention is a method for forming thermal regulation channels in a tool intended to manufacture at least one part by molding a material in the tooling, then by cooling the part by means of at least one heat transfer fluid circulating in heat regulation channels up to a predetermined mold release temperature, then by demolding the piece out of the tooling, the method comprising the steps of:
  • simulate the temperatures that are induced by heat transfer between the workpiece and the tool and between a moment of introduction of the material into the tooling and the moment of demolding of the workpiece;
  • determining a thermal field of induced temperatures in a reference volume comprising the workpiece and an intermediate volume extending between the outer surface of the workpiece and a reference surface located in the tooling;
  • locate in the thermal field so-called quasi-stationary regions, in each of which the displacement of at least one isothermal surface during a reference period has an amplitude less than a predetermined displacement limit, said reference period being between the instant introduction of the material into the tooling and the moment of demolding of the workpiece; and
  • within each quasi-stationary region, selecting an isothermal surface to define at least a portion of a peripheral surface of a respective thermal control channel.

En d'autres termes, les canaux de régulation thermique sont définis, en position et en dimension, en simulant la variation temporelle des températures induites dans l'outillage au voisinage de la pièce par les quantités de chaleur échangées entre pièce et outillage. La position et la dimension d'un canal de régulation thermique sont alors déterminées par les zones stationnaires et les surfaces isothermes. De même, les paramètres du procédé de moulage, tels que la température d'un fluide caloporteur et la durée d'un cycle de moulage, peuvent être déterminés à partir des surfaces isothermes sélectionnées.In other words, the thermal control channels are defined, in position and in size, by simulating the temporal variation of the temperatures induced in the tooling in the vicinity of the workpiece by the amounts of heat exchanged between workpiece and tooling. The position and size of a thermal control channel are then determined by the stationary zones and the isothermal surfaces. Similarly, the parameters of the molding process, such as the temperature of a heat transfer fluid and the duration of a molding cycle, can be determined from the selected isothermal surfaces.

Ainsi, un tel procédé de formation de ces canaux permet d'optimiser la régulation thermique de l'outillage, donc de réguler efficacement l'outillage en température et d'obtenir des températures uniformes sur la surface de la pièce et dans le volume de la pièce lors du refroidissement de la pièce et/ou lors d'un préchauffage de l'outillage. La durée d'un cycle et/ou le taux de pièces défectueuses peuvent donc être réduits et la qualité de fabrication de chaque pièce peut être d'augmentée.Thus, such a method of forming these channels makes it possible to optimize the thermal regulation of the tooling, thus to effectively regulate the tooling in temperature and to obtain uniform temperatures on the surface of the workpiece and in the volume of the workpiece. part during the cooling of the part and / or during a preheating of the tooling. The duration of a cycle and / or the rate of defective parts can therefore be reduced and the manufacturing quality of each part can be increased.

Dans la présente demande, le terme « canal » désigne une cavité qui est réalisée dans la matière de l'outillage et qui est alimentée en fluide caloporteur par au moins un circuit thermorégulateur.In the present application, the term "channel" designates a cavity which is made in the material of the tool and which is supplied with heat transfer fluid by at least one thermoregulator circuit.

Dans la présente demande, l'expression « champ thermique » désigne un tenseur associant un niveau de température simulée à chaque coordonnée spatiale et temporelle d'un point du volume de référence.In the present application, the term "thermal field" denotes a tensor associating a simulated temperature level with each spatial and temporal coordinate of a point of the reference volume.

Dans un procédé conforme à l'invention, l'étape consistant à « sélectionner une surface isotherme pour définir au moins une portion d'une surface périphérique d'un canal de régulation thermique » n'implique pas nécessairement que cette portion de surface périphérique soit définie de manière rigoureusement confondue avec la surface isotherme sélectionnée. En effet, la définition d'un canal de régulation thermique intègre aussi des contraintes d'usinage, qui varient suivant le mode d'usinage du canal. Ainsi, le perçage ne permet pas de réaliser un canal de forme complexe, notamment courbe ; dans ce cas, le canal sera défini ou dessiné de manière approximative en « s'appuyant » sur la surface isotherme. Inversement, un procédé génératif, tel que la fusion au laser, permet de construire un canal de forme très complexe ; dans ce cas, le canal pourra être défini ou dessiné de manière quasiment identique à la surface isotherme sélectionnée.In a method according to the invention, the step of "selecting an isothermal surface to define at least a portion of a peripheral surface of a thermal control channel" does not necessarily imply that this peripheral surface portion is defined strictly coincides with the selected isothermal surface. Indeed, the definition of a thermal control channel also incorporates machining constraints, which vary according to the machining mode of the channel. Thus, drilling does not make it possible to produce a channel of complex shape, in particular a curve; in this case, the channel will be defined or drawn roughly by "leaning" on the isothermal surface. Conversely, a generative process, such as laser fusion, allows to build a channel of very complex shape; in this case, the channel can be defined or drawn almost identically to the selected isothermal surface.

Dans la présente demande, le terme «fluide caloporteur » désigne un fluide qui a pour fonction de transporter la chaleur entre deux ou plusieurs sources présentant des températures différentes , c'est-à-dire d'apporter ou de retirer une quantité de chaleur à un élément solide . En d'autres termes, le terme «fluide caloporteur » équivaut à «fluide de régulation thermique ».In the present application, the term "coolant" means a fluid whose function is to transport heat between two or more sources having different temperatures, that is to say to bring or remove a quantity of heat to a solid element. In other words, the term "heat transfer fluid" is equivalent to "thermal control fluid".

En d'autres termes, le volume de référence comprend toute ou partie de la pièce plus un volume intermédiaire s'étendant entre la surface externe de la pièce et une surface de référence, laquelle est située dans l'outillage, donc hors de la pièce.In other words, the reference volume comprises all or part of the part plus an intermediate volume extending between the outer surface of the workpiece and a reference surface, which is located in the tooling, therefore outside the workpiece .

Selon un mode de réalisation, l'étape pour simuler les températures induites par lesdits transferts de chaleur comprend les étapes :

  • réaliser une dilatation morphologique de la surface externe de la pièce, de façon à définir une surface dilatée formant ladite surface de référence ;
  • réaliser une érosion morphologique de la surface externe de la pièce, de façon à définir une surface érodée ;
  • déterminer une distribution de températures d'au moins un fluide caloporteur sur la surface de référence de sorte que :
    • d'une part, la moyenne des températures simulées sur la surface érodée est approximativement égale à la température de démoulage prédéterminée à la fin du refroidissement ; et
    • d'autre part, la température simulée en chaque point de la surface externe de la pièce est approximativement égale à la moyenne des températures calculées sur la surface externe de la pièce à la fin du refroidissement ;
According to one embodiment, the step for simulating the temperatures induced by said heat transfers comprises the steps:
  • performing a morphological dilation of the outer surface of the workpiece, so as to define an expanded surface forming said reference surface;
  • perform a morphological erosion of the outer surface of the room, so as to define an eroded surface;
  • determining a temperature distribution of at least one heat transfer fluid on the reference surface so that:
    • on the one hand, the average of the simulated temperatures on the eroded surface is approximately equal to the predetermined demolding temperature at the end of the cooling; and
    • on the other hand, the simulated temperature at each point of the external surface of the part is approximately equal to the average of the temperatures calculated on the external surface of the part at the end of the cooling;

Dans un tel procédé, l'étape pour déterminer le champ thermique comprend un calcul basé sur ladite distribution de températures sur la surface de référence.In such a method, the step of determining the thermal field comprises a calculation based on said temperature distribution on the reference surface.

Ainsi, une telle dilatation permet de définir la surface de référence. Une telle érosion permet de définir une surface fictive délimitant la phase solide ou gaine solide et la phase fondue de la matière introduite dans l'outillage.Thus, such an expansion makes it possible to define the reference surface. Such an erosion makes it possible to define a fictitious surface delimiting the solid phase or solid sheath and the molten phase of the material introduced into the tooling.

Selon un mode de réalisation, l'érosion morphologique est réalisée au moyen d'un élément structurant, par exemple une sphère, dont une dimension est sensiblement égale à une épaisseur prédéterminée d'une gaine solide de la pièce en vue du démoulage de la pièce.According to one embodiment, the morphological erosion is carried out by means of a structuring element, for example a sphere, a dimension of which is substantially equal to a predetermined thickness of a solid sheath of the workpiece for demolding the workpiece. .

Ainsi, une telle érosion morphologique permet de définir des canaux de régulation thermique qui assurent un refroidissement uniforme de la gaine solide de la pièce.Thus, such a morphological erosion makes it possible to define thermal regulation channels which ensure uniform cooling of the solid sheath of the part.

Selon une alternative au mode de réalisation précédent, l'étape pour simuler les températures induites par lesdits transferts de chaleur comprend les étapes :

  • réaliser une dilatation morphologique de la surface externe de la pièce, de façon à définir une surface dilatée formant ladite surface de référence ;
  • déterminer une distribution de températures d'au moins un fluide caloporteur sur la surface de référence de sorte que la température simulée en chaque point de la surface externe de la pièce est approximativement égale à un seuil de température prédéterminé sur la surface externe de la pièce à la fin du refroidissement ;
et dans lequel l'étape pour déterminer le champ thermique comprend un calcul basé sur ladite distribution de températures sur la surface de référence.According to an alternative to the previous embodiment, the step for simulating the temperatures induced by said heat transfer comprises the steps:
  • performing a morphological dilation of the outer surface of the workpiece, so as to define an expanded surface forming said reference surface;
  • determining a temperature distribution of at least one coolant on the reference surface such that the simulated temperature at each point on the outer surface of the workpiece is approximately equal to a predetermined temperature threshold on the outer surface of the workpiece. the end of the cooling;
and wherein the step of determining the thermal field comprises a calculation based on said temperature distribution on the reference surface.

Ainsi, une telle variante du procédé nécessite relativement peu d'étapes de conception.Thus, such a variant of the process requires relatively few design steps.

Avantageusement, la dilatation morphologique est réalisée au moyen d'un élément structurant, par exemple une sphère, dont une dimension est supérieure à une distance prédéterminée pour assurer la résistance mécanique de l'outillage après formation des canaux de régulation thermique.Advantageously, the morphological dilation is carried out by means of a structuring element, for example a sphere, a dimension of which is greater than a predetermined distance to ensure the mechanical strength of the tooling after formation of the thermal regulation channels.

Ainsi, une telle dilatation morphologique permet de réaliser un outillage solide, dans lequel les canaux de régulation thermique ne diminuent pas significativement la résistance mécanique élevée de l'outillage.Thus, such a morphological expansion makes it possible to produce a solid tool, in which the thermal control channels do not significantly reduce the high mechanical strength of the tooling.

Selon un mode de réalisation, le procédé comprend en outre une étape ultérieure consistant à former totalement une surface périphérique d'un canal de régulation thermique respectif en fermant ladite portion de surface périphérique lorsque ladite portion de surface périphérique est partiellement délimitée par la surface de référence.According to one embodiment, the method further comprises a subsequent step of completely forming a peripheral surface a respective thermal control channel by closing said peripheral surface portion when said peripheral surface portion is partially delimited by the reference surface.

Ainsi, un canal de régulation thermique peut être complétement défini dans toute sa surface.Thus, a thermal regulation channel can be completely defined throughout its surface.

Selon un mode de réalisation, une température respective de fluide caloporteur est associée à chaque canal de régulation thermique, lorsque les surfaces isothermes sélectionnées respectivement à l'intérieur de régions quasi-stationnaires distinctes correspondent à des températures différentes.According to one embodiment, a respective heat transfer fluid temperature is associated with each thermal control channel, when the isothermal surfaces selected respectively within distinct quasi- stationary regions correspond to different temperatures.

Ainsi, un tel procédé permet de maîtriser les températures dans la pièce en faisant circuler dans l'outillage des fluides caloporteurs portés à des températures distinctes.Thus, such a method makes it possible to control the temperatures in the room by circulating in the tooling heat transfer fluids heated to different temperatures.

Selon un mode de réalisation, le nombre de températures de fluide caloporteur différentes qui sont associées aux canaux de régulation thermique est limité au nombre de circuits thermorégulateurs destinés à alimenter les canaux de régulation thermique en fluide caloporteur.According to one embodiment, the number of different heat transfer fluid temperatures that are associated with the thermal control channels is limited to the number of thermoregulatory circuits for supplying heat transfer fluid heat transfer channels.

Ainsi, un tel procédé permet de prévoir autant de circuits thermorégulateurs distincts que d'isothermes sélectionnées.Thus, such a method makes it possible to provide as many separate thermoregulatory circuits as selected isotherms.

Selon un mode de réalisation, la forme d'un canal de régulation thermique respective est définie de façon à minimiser les pertes de charge générées lors des écoulements du fluide caloporteur.According to one embodiment, the shape of a respective thermal regulation channel is defined so as to minimize the pressure drops generated during the flows of the coolant.

Ainsi, une telle forme de canal permet de limiter le débit du fluide caloporteur à faire circuler, car les pertes de charge générées par ce canal sont faibles.Thus, such a channel shape makes it possible to limit the flow rate of the coolant to be circulated, because the pressure losses generated by this channel are small.

Selon un mode de réalisation, chaque surface isotherme est sélectionnée à l'intérieur d'une région quasi-stationnaire respective de façon à écarter les canaux de régulation thermique et la surface externe de la pièce de sorte que l'outillage résiste aux contraintes thermomécaniques susceptibles de s'exercer au cours de la fabrication d'une pièce.According to one embodiment, each isothermal surface is selected within a respective quasi-stationary region so as to separate the thermal regulation channels and the outer surface of the part so that the tooling withstands the thermomechanical stresses likely to practice during the manufacture of a piece.

Ainsi, un tel critère de sélection d'une surface isotherme évite de fragiliser l'outillage.Thus, such a criterion for selecting an isothermal surface avoids weakening the tooling.

Selon un mode de réalisation, chaque surface isotherme est sélectionnée à l'intérieur d'une région quasi-stationnaire respective de sorte que, entre l'instant d'introduction de la matière dans l'outillage et l'instant de démoulage de la pièce, la température d'une surface isotherme respective est comprise dans un intervalle prédéterminé en fonction de la matière injectée.According to one embodiment, each isothermal surface is selected within a respective quasi-stationary region so that, between the moment of introduction of the material into the tool and the moment of demolding of the workpiece, the temperature of a respective isothermal surface is within a predetermined range depending on the material injected.

Ainsi, un tel critère de sélection d'une surface isotherme permet de tenir compte des recommandations du fabricant de la matière, ce qui garantit la qualité de chaque pièce moulée.Thus, such a selection criterion for an insulated surface makes it possible to take into account the recommendations of the manufacturer of the material, which guarantees the quality of each molded part.

Selon un mode de réalisation, la distribution de températures d'au moins un fluide caloporteur sur la surface de référence est déterminée au moyen d'un algorithme d'optimisation impliquant la méthode dite du gradient conjugué, de préférence couplé avec la technique dite du multiplicateur de Lagrange.According to one embodiment, the temperature distribution of at least one coolant on the reference surface is determined by means of an optimization algorithm involving the so-called conjugated gradient method, preferably coupled with the so-called multiplier technique. of Lagrange.

Ainsi, un tel algorithme contribue à optimiser la formation des canaux de régulation thermique.Thus, such an algorithm contributes to optimizing the formation of heat regulation channels.

De plus, la présente invention a pour objet un outillage destiné à fabriquer au moins une pièce par moulage d'une matière, l'outillage comprenant des canaux de régulation thermique, l'outillage étant caractérisé en ce que tout ou partie des canaux de régulation thermique sont formés en mettant en oeuvre un procédé selon l'invention.In addition, the subject of the present invention is a tool intended to manufacture at least one part by molding a material, the tooling comprising heat regulation channels, the tool being characterized in that all or part of the control channels are formed by implementing a method according to the invention.

Ainsi, un tel outillage présente une régulation thermique optimisée, pour réaliser une régulation thermique efficace et obtenir des températures uniformes sur et dans la pièce lors du refroidissement de la pièce. La durée d'un cycle et/ou le taux de pièces défectueuses peuvent donc être réduits et la qualité de fabrication de chaque pièce peut être augmentée.Thus, such tooling has optimized thermal regulation, to achieve effective thermal control and obtain uniform temperatures on and in the room during the cooling of the room. The duration of a cycle and / or the rate of defective parts can therefore be reduced and the manufacturing quality of each part can be increased.

Par ailleurs, la présente invention a pour objet un produit programme d'ordinateur qui met en oeuvre un algorithme réalisant un procédé selon l'invention.Moreover, the subject of the present invention is a computer program product which implements an algorithm implementing a method according to the invention.

Ainsi, un tel produit programme d'ordinateur permet de concevoir de manière automatique et optimisée la formation des canaux de refroidissement dans l'outillage, notamment à partir de la géométrie de la pièce, de la matière à injecter et des recommandations du fabricant de la matière en vue de son moulage.Thus, such a computer program product makes it possible to automatically and optimally design the formation of cooling channels in the tooling, in particular from the geometry of the part, the material to be injected and the recommendations of the manufacturer of the machine. material for molding purposes.

Les modes de réalisation de l'invention et les variantes de l'invention mentionnés ci-avant peuvent être pris isolément ou selon toute combinaison techniquement possible.The embodiments of the invention and the variants of the invention mentioned above can be taken individually or in any combination technically possible.

La présente invention sera bien comprise et ses avantages ressortiront aussi à la lumière de la description qui va suivre, donnée uniquement à titre d'exemple non limitatif et faite en référence aux dessins annexés, dans lesquels :

  • la figure 1 est une vue en perspective d'une première pièce à mouler pour laquelle un outillage conforme à un premier mode de réalisation de l'invention doit être formé selon un procédé conforme à l'invention ;
  • la figure 2 est une vue correspondant à une section suivant le plan II à la figure 1 et illustrant une étape du procédé conforme à l'invention ;
  • la figure 3 est une vue similaire à une partie de la figure 2 et illustrant une étape ultérieure du procédé conforme à l'invention ;
  • la figure 4 est une vue similaire à la figure 3 et illustrant une étape ultérieure du procédé conforme à l'invention ;
  • la figure 5 est une vue similaire à la figure 4 et illustrant une étape ultérieure du procédé conforme à l'invention ;
  • la figure 6 est une vue en section d'une partie de l'outillage conforme au premier mode de réalisation de l'invention ;
  • la figure 7 est une vue en perspective, similaire à la figure 1, d'une deuxième pièce à mouler pour laquelle un outillage conforme à un deuxième mode de réalisation de l'invention doit être formé selon un procédé conforme à l'invention ;
  • la figure 8 est une vue correspondant à une perspective et illustrant la même étape du procédé conforme à l'invention que la figure 2 ;
  • la figure 9 est une vue similaire à la figure 8 et illustrant la même étape du procédé conforme à l'invention que la figure 4 ;
  • la figure 10 est une vue similaire à la figure 9 et illustrant la même étape du procédé conforme à l'invention que la figure 5 ; et
  • la figure 11 est une vue similaire à la figure 10 et illustrant une étape ultérieure du procédé conforme à l'invention.
The present invention will be well understood and its advantages will also emerge in the light of the description which follows, given only by way of non-limiting example and with reference to the accompanying drawings, in which:
  • the figure 1 is a perspective view of a first molding piece for which a tool according to a first embodiment of the invention is to be formed according to a method according to the invention;
  • the figure 2 is a view corresponding to a section following plan II to the figure 1 and illustrating a step of the process according to the invention;
  • the figure 3 is a view similar to some of the figure 2 and illustrating a subsequent step of the process according to the invention;
  • the figure 4 is a view similar to the figure 3 and illustrating a subsequent step of the process according to the invention;
  • the figure 5 is a view similar to the figure 4 and illustrating a subsequent step of the process according to the invention;
  • the figure 6 is a sectional view of a portion of the tool according to the first embodiment of the invention;
  • the figure 7 is a perspective view, similar to the figure 1 a second molding piece for which a tool according to a second embodiment of the invention is to be formed according to a method according to the invention;
  • the figure 8 is a view corresponding to a perspective and illustrating the same step of the method according to the invention that the figure 2 ;
  • the figure 9 is a view similar to the figure 8 and illustrating the same step of the process according to the invention that the figure 4 ;
  • the figure 10 is a view similar to the figure 9 and illustrating the same step of the process according to the invention that the figure 5 ; and
  • the figure 11 is a view similar to the figure 10 and illustrating a subsequent step of the process according to the invention.

La figure 1 illustre un profilé 4 dont le moulage est réalisé selon un procédé conforme à l'invention et au moyen d'un outillage 2.3 conforme à l'invention. Comme le montre la figure 6, l'outillage 2.3 est composé essentiellement de deux parties d'outillage 2 et 3. Une section transversale en « T » forme la base du profilé 4. L'outillage 2.3 est formé de deux parties de moule 2 et 3, lesquelles délimitent une cavité moulante.The figure 1 illustrates a section 4, the molding of which is carried out according to a method according to the invention and by means of a tooling 2.3 according to the invention. As shown in figure 6 , the tooling 2.3 is essentially composed of two tooling parts 2 and 3. A "T" -shaped cross-section forms the base of the profile 4. The tooling 2.3 is formed of two mold parts 2 and 3, which delimit a molding cavity.

L'outillage 2.3 est destiné à fabriquer une série de profilés 4 en réalisant les opérations :

  • introduire dans la cavité moulante de l'outillage 2.3 une matière thermoplastique, par exemple du polyamide 6,6, tel que celui commercialisé sous la marque Technyl® ;
  • mouler la matière thermoplastique, ce qui permet de former le profilé 4 ;
  • refroidir le profilé 4 au moyen d'un ou plusieurs fluide(s) caloporteur(s) circulant dans des canaux 1 de régulation thermique de l'outillage 2.3, qui sont illustrés à la figure 6 et qui ont été formés suivant un procédé conforme à l'invention et décrit ci-après ; le profilé 4 est ainsi refroidi jusqu'à une température de démoulage prédéterminée ou température de démoulage « cible » ; et
  • démouler le profilé 4 hors de l'outillage 2.3.
The tooling 2.3 is intended to manufacture a series of profiles 4 by carrying out the operations:
  • introducing into the molding cavity of the tooling 2.3 a thermoplastic material, for example polyamide 6,6, such as that marketed under the trademark Technyl®;
  • molding the thermoplastic material, which allows to form the profile 4;
  • cooling the section 4 by means of one or more heat transfer fluid (s) circulating in heat regulation channels 1 of the tooling 2.3, which are illustrated in FIG. figure 6 and which have been formed according to a process according to the invention and described hereinafter; the section 4 is thus cooled to a predetermined demolding temperature or "target" mold release temperature; and
  • demolding the profile 4 out of the tool 2.3.

Comme le montre la figure 2, le profilé 4 présente une surface externe 4.1.As shown in figure 2 , the profile 4 has an outer surface 4.1.

Le procédé illustré par les figures 1 à 6 comprend une étape dans laquelle on simule les températures résultant de transferts de chaleur du profilé 4 à l'outillage 2.3, entre l'instant d'introduction de la matière dans l'outillage 2.3 et l'instant de démoulage du profilé 4 hors de la cavité moulante de l'outillage 2.3.The process illustrated by the Figures 1 to 6 comprises a step in which the temperatures resulting from heat transfers from the section 4 to the tooling 2.3 are simulated between the instant of introduction of the material in the tooling 2.3 and the moment of demolding of the profile 4 out of the molding cavity of the tool 2.3.

Comme le montre la figure 4, le procédé illustré par les figures 1 à 6 comprend une étape dans laquelle on détermine le champ thermique des températures induites dans un volume de référence 17.4 qui comprend le profilé 4 et le volume intermédiaire 17 qui s'étend du profilé 4 à une surface de référence 11 qui est située dans l'outillage 2.3.As shown in figure 4 , the process illustrated by the Figures 1 to 6 comprises a step in which the thermal field of the induced temperatures is determined in a reference volume 17.4 which comprises the profile 4 and the intermediate volume 17 which extends from the profile 4 to a reference surface 11 which is located in the tooling 2.3 .

Le volume intermédiaire 17 correspond au volume d'une partie de l'outillage 2.3 qui est proche de la cavité moulante où doit être injectée la matière thermoplastique. La cavité moulante de l'outillage 2.3 correspond à la surface externe 4.1 du profilé 4. Dans le volume de référence 17.4 et dans le volume intermédiaire 17, les températures sont induites par les transferts de chaleur qui se produisent entre la matière thermoplastique injectée pour former le profilé 4 et l'outillage 2.3.The intermediate volume 17 corresponds to the volume of a portion of the tooling 2.3 which is close to the molding cavity where the thermoplastic material is to be injected. The molding cavity of the tooling 2.3 corresponds to the external surface 4.1 of the profile 4. In the reference volume 17.4 and in the intermediate volume 17, the temperatures are induced by the transfers of heat that occur between the thermoplastic material injected to form the profile 4 and the tooling 2.3.

Le « champ thermique » est un tenseur associant un niveau de température simulée à chaque coordonnée spatiale et temporelle d'un point du volume de référence 17.4.The "thermal field" is a tensor associating a simulated temperature level with each spatial and temporal coordinate of a point of the reference volume 17.4.

La détermination de ce champ thermique permet d'identifier des surfaces isothermes 23, c'est-à-dire chaque surface qui réunit, à un instant donné, des points du volume intermédiaire 17 qui sont à la même température. Sur la figure 4, chaque surface isotherme 23 est matérialisée par une ligne courbe disjointe des surfaces isothermes 23 adjacentes.The determination of this thermal field makes it possible to identify isothermal surfaces 23, that is to say each surface which brings together, at a given moment, points of the intermediate volume 17 which are at the same temperature. On the figure 4 each isothermal surface 23 is materialized by a disjoint curved line of the adjacent isothermal surfaces 23.

Pour simuler les températures induites par les transferts de chaleur, le procédé illustré par les figures 1 à 6 comprend une étape dans laquelle on réalise une dilatation morphologique de la surface externe 4.1 du profilé 4, de façon à définir la surface de référence 11, ci-après dénommée surface dilatée 11.To simulate the temperatures induced by the heat transfers, the process illustrated by the Figures 1 to 6 comprises a step in which morphological expansion of the outer surface 4.1 of the profile 4 is carried out so as to define the reference surface 11, hereinafter referred to as the expanded surface 11.

Les canaux 1 remplissent une fonction de régulation thermique. D'une part, ils canalisent l'écoulement d'un fluide caloporteur qui est plus froid que la température d'introduction de la matière dans l'empreinte ou cavité moulante de l'outillage 2.3. Un tel écoulement provoque des transferts de chaleur entre le profilé 4 et le fluide caloporteur, ce qui permet de refroidir le profilé 4. D'autre part, le cas échéant, ils canalisent l'écoulement d'un fluide caloporteur pour préchauffer l'outillage 2.3, ce qui améliore la qualité des profilés 4 moulés.Channels 1 fulfill a thermal regulation function. On the one hand, they channel the flow of a heat transfer fluid which is colder than the temperature of introduction of the material in the cavity or mold cavity of the tooling 2.3. Such a flow causes heat transfer between the section 4 and the coolant, which allows to cool the profile 4. On the other hand, if necessary, they channel the flow of a heat transfer fluid to preheat the tooling 2.3, which improves the quality of the molded profiles 4.

Dans l'exemple des figures 1 à 6, l'élément structurant guidant la dilatation morphologique est une première sphère, non représentée, dont le diamètre est par exemple d'environ 4 fois l'épaisseur du profilé. Le diamètre de la sphère est supérieur à une distance prédéterminée pour assurer la résistance mécanique de l'outillage 2.3 après formation des canaux de régulation thermique 1. Cette distance est par exemple supérieure à environ 3 mm, voire à environ 4 mm.In the example of Figures 1 to 6 , the structuring element guiding the morphological dilation is a first sphere, not shown, whose diameter is for example about 4 times the thickness of the profile. The diameter of the sphere is greater than a predetermined distance to ensure the mechanical strength of the tooling 2.3 after formation of the thermal control channels 1. This distance is for example greater than about 3 mm, or even about 4 mm.

De plus, le procédé illustré par les figures 1 à 6 comprend une étape dans laquelle on réalise une érosion morphologique de la surface externe 4.1 du profilé 4, de façon à définir une surface érodée 12.In addition, the process illustrated by Figures 1 to 6 comprises a step in which morphological erosion of the outer surface 4.1 of the profile 4 is performed so as to define an eroded surface 12.

Dans l'exemple des figures 1 à 6, l'élément structurant guidant l'érosion morphologique est une deuxième sphère, non représentée, dont une dimension est sensiblement égale à une épaisseur prédéterminée d'une gaine solide du profilé 4 en vue du démoulage du profilé 4. L'épaisseur de la gaine solide est prédéterminée notamment en fonction de la matière moulée et de la géométrie de la pièce, ici du profilé 4, de sorte que le profilé 4 présente une résistance mécanique permettant son démoulage sans altération géométrique. Après le démoulage, la partie du profilé 4 qui n'est pas encore solidifiée continue de refroidir, puis se solidifie aussi. Le profilé 4 présente alors sa résistance mécanique définitive.In the example of Figures 1 to 6 , the structuring element guiding the morphological erosion is a second sphere, not shown, a dimension of which is substantially equal to a predetermined thickness of a solid sheath of the profile 4 for the demolding of the profile 4. The thickness of the solid sheath is predetermined in particular depending on the molded material and the geometry of the part, here the profile 4, so that the profile 4 has a mechanical resistance allowing its demolding without geometric alteration. After demolding, the portion of the section 4 which has not yet solidified continues to cool, then solidifies too. The profile 4 then has its final mechanical strength.

Ensuite, le procédé illustré par les figures 1 à 6 comprend une étape dans laquelle on détermine une distribution de températures d'au moins un fluide caloporteur sur la surface dilatée 11 de sorte que :

  • d'une part, la moyenne des températures simulées sur la surface érodée 12 est approximativement égale à la température de démoulage prédéterminée à la fin du refroidissement ; et
  • d'autre part, la température simulée en chaque point de la surface externe 4.1 du profilé 4 est approximativement égale à la moyenne des températures calculées sur la surface externe 4.1 à la fin du refroidissement.
Then, the process illustrated by Figures 1 to 6 comprises a step in which a temperature distribution of at least one heat transfer fluid is determined on the expanded surface 11 so that:
  • on the one hand, the average of the simulated temperatures on the eroded surface 12 is approximately equal to the predetermined demolding temperature at the end of the cooling; and
  • on the other hand, the simulated temperature at each point of the outer surface 4.1 of the section 4 is approximately equal to the average of the temperatures calculated on the external surface 4.1 at the end of the cooling.

Dans la présente demande, l'expression «distribution de températures» désigne un tenseur associant un niveau de température simulée à chaque coordonnée spatiale et temporelle d'un point d'une surface, ici de la surface de référence 11.In the present application, the expression "temperature distribution" designates a tensor associating a simulated temperature level with each spatial and temporal coordinate of a point of a surface, here of the reference surface 11.

Cette distribution de températures sur la surface dilatée 11 est obtenue en simulant les transferts de chaleur entre le profilé 4, l'outillage 2.3 et un fluide caloporteur pour le refroidissement. Cette distribution de températures sur la surface dilatée 11 est déterminée par calcul au moyen d'un algorithme d'optimisation impliquant la méthode dite du gradient conjugué, de préférence couplé avec la technique dite du multiplicateur de Lagrange.This temperature distribution on the expanded surface 11 is obtained by simulating the heat transfer between the section 4, the tooling 2.3 and a heat transfer fluid for cooling. This temperature distribution on the expanded surface 11 is determined by calculation by means of an optimization algorithm involving the so-called conjugate gradient method, preferably coupled with the so-called Lagrange multiplier technique.

Pour déterminer le champ thermique, le procédé illustré aux figures 1 à 6 comprend un calcul basé sur cette distribution de températures sur la surface dilatée 11.To determine the thermal field, the process illustrated in Figures 1 to 6 includes a calculation based on this temperature distribution on the dilated surface 11.

Dans l'exemple des figures, les points chauds du volume intermédiaire 17 sont matérialisés par des zones en pointillés clairsemé à la figure 4 et les points froids du volume intermédiaire 17 sont matérialisés par des zones en pointillés denses à la figure 4.In the example of the figures, the hot spots of the intermediate volume 17 are represented by dashed zones sparse at the figure 4 and the cold points of the intermediate volume 17 are materialized by dashed areas dense with the figure 4 .

Le procédé illustré par les figures 1 à 6 comprend en outre une étape dans laquelle on localise dans le champ thermique des régions dites quasi-stationnaires 21. Sur la figure 4, chaque région quasi-stationnaire 21 est repérée globalement par une ellipse.The process illustrated by the Figures 1 to 6 further comprises a step in which quasi-stationary regions 21 are located in the thermal field. figure 4 each quasi-stationary region 21 is globally marked by an ellipse.

Dans la présente demande, une région quasi-stationnaire 21 du volume intermédiaire 17 est une région dans laquelle le déplacement d'au moins une surface isotherme 23 durant une période de référence reste approximativement constant. En d'autres termes, ce déplacement présente une amplitude inférieure à une limite de déplacement prédéterminée.In the present application, a quasi-stationary region 21 of the intermediate volume 17 is a region in which the displacement of at least one isothermal surface 23 during a reference period remains approximately constant. In other words, this displacement has an amplitude less than a predetermined displacement limit.

Dans la présente demande, le terme « déplacement » appliqué à une surface isotherme recouvre toute variation de position ou de géométrie de la surface isotherme.In the present application, the term "displacement" applied to an isothermal surface covers any variation in position or geometry of the isothermal surface.

En effet, la position et/ou la géométrie de chaque surface isotherme 23 varie(nt), au cours d'un cycle de moulage, en fonction des transferts de chaleur entre le profilé 4 et l'outillage 2.3. La période de référence est comprise entre l'instant d'introduction de la matière dans l'outillage 2.3 et l'instant de démoulage du profilé 4.Indeed, the position and / or the geometry of each isothermal surface 23 varies (nt), during a molding cycle, as a function of the heat transfer between the section 4 and the tooling 2.3. The reference period is between the instant of introduction of the material into the tooling 2.3 and the moment of demolding of the profile 4.

Dans l'exemple des figures, la période de référence correspond à un cycle de moulage complet d'un profilé 4. La période de référence comprend au moins deux phases distinctes. La première phase s'étend depuis l'instant d'introduction de la matière dans l'outillage 2.3 jusqu'à l'instant de démoulage du profilé 4. La deuxième phase s'étend depuis l'instant de démoulage du profilé 4 précédent jusqu'à une nouvelle introduction de matière pour mouler le profilé suivant.In the example of the figures, the reference period corresponds to a complete molding cycle of a section 4. The reference period comprises at least two distinct phases. The first phase extends from the moment of introduction of the material into the tooling 2.3 until the moment of release of the profile 4. The second phase extends from the moment of demolding of the previous section 4 until to a new introduction of material for molding the next profile.

Alternativement, une période de référence plus courte peut être comprise entre l'instant d'introduction de la matière dans l'outillage 2.3 et l'instant de démoulage du profilé 4. La période de référence est choisie de sorte qu'elle corresponde à la première phase d'un cycle de moulage complet.Alternatively, a shorter reference period can be between the instant of introduction of the material in the tooling 2.3 and the moment of release of the profile 4. The reference period is chosen so that it corresponds to the first phase of a complete molding cycle.

Ensuite, comme le montre la figure 5, le procédé illustré par les figures 1 à 6 comprend une étape dans laquelle on sélectionne, à l'intérieur de chaque région quasi-stationnaire 21, une surface isotherme 23 pour définir des portions 23.1, 23.2 et 23.3 de surfaces périphériques pour les canaux 1 respectifs.Then, as shown in figure 5 , the process illustrated by the Figures 1 to 6 comprises a step in which an isothermal surface 23 is selected within each quasi-stationary region 21 to define portions 23.1, 23.2 and 23.3 of peripheral surfaces for the respective channels 1.

En section dans le plan de la figure 5, chaque portion 23.1, 23.2 ou 23.3 est globalement en forme d'ellipse. Les portions 23.1, 23.2 et 23.3 correspondent à des surfaces isothermes 23 dont le niveau de température simulée est d'environ 305 K (degrés Kelvin). Alternativement, des portions distinctes peuvent correspondre à des surfaces isothermes dont les niveaux de températures simulées sont distincts, par exemple respectivement d'environ 324 K, 330 K et 335 K (degrés Kelvin). Une telle sélection de plusieurs isothermes permet d'optimiser la régulation thermique en fonction de la géométrie de la pièce à mouler.In section in the plan of the figure 5 each portion 23.1, 23.2 or 23.3 is generally elliptical. Portions 23.1, 23.2 and 23.3 correspond to isothermal surfaces 23 whose simulated temperature level is approximately 305 K (degrees Kelvin). Alternatively, distinct portions may correspond to isothermal surfaces whose simulated temperature levels are distinct, for example respectively about 324 K, 330 K and 335 K (degrees Kelvin). Such a selection of several isotherms makes it possible to optimize the thermal regulation as a function of the geometry of the piece to be molded.

Lorsque une portion 23.1, 23.2 ou 23.3 est partiellement délimitée par la surface dilatée 11, le procédé illustré par les figures 1 à 6 peut en outre comprendre une étape ultérieure consistant à former totalement la surface périphérique respective de chaque canal 1 en fermant chaque portion 23.1, 23.2 ou 23.3. Cette fermeture est formée en fonction du procédé de réalisation des canaux 1.When a portion 23.1, 23.2 or 23.3 is partially delimited by the expanded surface 11, the method illustrated by the Figures 1 to 6 may further comprise a subsequent step of completely forming the respective peripheral surface of each channel 1 by closing each portion 23.1, 23.2 or 23.3. This closure is formed according to the method of making the channels 1.

Dans le cas d'un usinage traditionnel, par exemple quand les canaux 1 sont réalisés par perçage ou fraisage, les canaux sont fermés en suivant des tracés de formes relativement simples. De tels canaux sont illustrés en pointillés à la figure 6 avec la référence 10. Dans la mesure où le tracé des canaux 10 diffère des surfaces isothermes 23 sélectionnées, la régulation thermique n'est pas tout à fait optimale.In the case of traditional machining, for example when the channels 1 are made by drilling or milling, the channels are closed by following relatively simple patterns. Such channels are illustrated in dashed lines at figure 6 With the reference 10. Since the channel pattern 10 differs from the selected isothermal surfaces 23, the thermal regulation is not quite optimal.

Dans le cas d'un usinage par un procédé génératif, tel que la fusion laser, les canaux sont fermés en suivant des tracés de formes relativement complexes, ce qui permet d'optimiser la régulation thermique. De tels canaux sont illustrés en trait continu à la figure 6 avec la référence 1. Dans la mesure où le tracé des canaux 1 épouse les surfaces isothermes 23 sélectionnées, la régulation thermique peut être optimale.In the case of machining by a generative process, such as laser melting, the channels are closed by following relatively complex patterns, which optimizes the thermal regulation. Such channels are illustrated in solid lines at the figure 6 with the reference 1. Insofar as the pattern of the channels 1 matches the selected isothermal surfaces 23, the thermal regulation can be optimal.

Dans la mesure où le profilé 4 s'étend suivant des génératrices perpendiculaires au plan de la figure 6, chaque canal 1 est tracé de manière rectiligne et perpendiculaire au plan de la figure 6. Un tel tracé minimise les pertes de charge générées lors des écoulements du fluide caloporteur.Insofar as the profile 4 extends along generatrices perpendicular to the plane of the figure 6 , each channel 1 is drawn in a rectilinear manner and perpendicular to the plane of the figure 6 . Such a layout minimizes the pressure losses generated during the flows of the heat transfer fluid.

Lors de la conception de l'outillage 2.3, chaque canal 1 peut en outre être tracé en fonction notamment de la cinématique d'ouverture de l'outillage 2.3, c'est-à-dire de séparation des parties d'outillage 2 et 3, et de la position dans l'outillage 2.3 des conduits d'alimentation en matière thermoplastique, usuellement dénommés « carottes ».During the design of the tooling 2.3, each channel 1 can also be traced in particular according to the opening kinematics of the tooling 2.3, that is to say the separation of the tooling parts 2 and 3 , and the position in the tooling 2.3 of thermoplastic supply ducts, usually called "carrots".

Lors de la formation des canaux 1 ou 10, le concepteur peut ainsi parvenir à une solution équilibrée entre les contraintes de régulation thermique et les autres fonctions que remplit l'outillage 2.3.During the formation of channels 1 or 10, the designer can thus achieve a balanced solution between the thermal regulation constraints and the other functions that the tooling 2.3 fulfills.

Dans un procédé conforme à l'invention, une température respective de fluide caloporteur, par exemple 330 K, peut être associée à un canal 1 respectif, dans le cas où les surfaces isothermes 23 sélectionnées à l'intérieur de régions quasi-stationnaires 21 distinctes correspondent à des températures différentes.In a process according to the invention, a respective heat transfer fluid temperature, for example 330 K, may be associated with a respective channel 1, in the case where the isothermal surfaces 23 selected within distinct quasi-stationary regions 21 correspond to different temperatures.

Dans l'exemple des figures, une température de fluide caloporteur est associée aux canaux 1. Le nombre de circuits thermorégulateurs non représentés pour alimenter en fluide caloporteur les canaux 1 est au minimum de un. Dans l'alternative où plusieurs isothermes sont sélectionnées, le nombre de circuits thermorégulateurs pour alimenter en fluide caloporteur les canaux peut être supérieur à un, par exemple égal à trois.In the example of the figures, a coolant temperature is associated with the channels 1. The number of thermoregulatory circuits not shown for supplying heat transfer fluid to the channels 1 is at least one. In the alternative where several isotherms are selected, the number of thermoregulatory circuits for supplying the heat transfer fluid to the channels may be greater than one, for example equal to three.

En outre, chaque surface isotherme 23 est sélectionnée à l'intérieur d'une région quasi-stationnaire respective 21 de façon à écarter chaque canal 1 et la surface externe 4.1 du profilé 4 de sorte que l'outillage 2.3 résiste aux contraintes thermomécaniques susceptibles de s'exercer au cours du moulage des profilés 4. A cet effet, une distance entre un canal 1 et la surface externe 4.1 du profilé 4 peut être supérieure à 3 mm voire à 4 mm.In addition, each isothermal surface 23 is selected inside a respective quasi-stationary region 21 so as to separate each channel 1 and the outer surface 4.1 of the profile 4 so that the tooling 2.3 withstands the thermomechanical stresses likely to during the molding of the profiles 4. For this purpose, a distance between a channel 1 and the outer surface 4.1 of the section 4 may be greater than 3 mm or even 4 mm.

Ainsi, l'outillage 2.3 comprend des canaux 1 formés en mettant en oeuvre un procédé conforme à l'invention. En d'autres termes, les formes des canaux 1 a été définie ou calculée en mettant en oeuvre ce procédé, puis l'outillage 2.3 a été usiné à partir des dimensions de ces formes des canaux 1. Dans ce but, on peut utiliser un produit programme d'ordinateur qui met en oeuvre un algorithme réalisant un tel procédé.Thus, the tooling 2.3 comprises channels 1 formed by implementing a method according to the invention. In other words, the shapes of the channels 1 have been defined or calculated by implementing this method, and then the tooling 2.3 has been machined from the dimensions of these shapes of the channels 1. For this purpose, it is possible to use a computer program product which implements an algorithm performing such a method.

Les figures 7 à 11 illustrent un procédé conforme à un deuxième mode de réalisation de l'invention pour former des canaux 101 dans un outillage 102.103 conforme à un deuxième mode de réalisation de l'invention. Dans la mesure où l'outillage 102.103 est similaire à l'outillage 2.3, la description de l'outillage 2.3 et le procédé correspondant donnée ci-avant en relation avec les figures 1 à 6 peut être transposée à l'outillage 102.103 et le procédé correspondant, à l'exception notable des différences énoncées ci-après.The Figures 7 to 11 illustrate a method according to a second embodiment of the invention for forming channels 101 in a tool 102.103 according to a second embodiment of the invention. Insofar as the tool 102.103 is similar to the tooling 2.3, the description of the tooling 2.3 and the corresponding method given above in relation to the Figures 1 to 6 can be transposed to the tool 102.103 and the corresponding method, with the notable exception of the differences set out below.

Un élément de l'outillage 102.103 identique ou correspondant, par sa structure ou par sa fonction, à un élément de l'outillage 2.3 porte la même référence numérique augmentée de 100. On définit ainsi des canaux 101, l'outillage 102.103 avec des parties de moules 102 et 103, une pièce 104 avec une surface externe 104.1, une surface dilatée 111, une surface érodée 112, un volume intermédiaire 117, un volume de référence 117.104, des régions quasi-stationnaires 121, des surfaces isothermes 123, des portions 123.1 et 123.2.An element of the tool 102.103 identical or corresponding, by its structure or by its function, to an element of the tooling 2.3 carries the same numerical reference increased by 100. Thus, channels 101, tool 102.103 are defined with parts of molds 102 and 103, a workpiece 104 with an outer surface 104.1, an expanded surface 111, an eroded surface 112, an intermediate volume 117, a reference volume 117.104, quasi-stationary regions 121, isothermal surfaces 123, portions 123.1 and 123.2.

Comme le montre la figure 7, la pièce 104 diffère du profilé 4, car la pièce 104 a globalement la forme d'un quart de boite. De même, l'outillage 102.103 diffère de l'outillage 2.3, car sa cavité moulante a globalement la forme d'un quart de parallélépipède.As shown in figure 7 , the piece 104 differs from the profile 4, because the piece 104 has the overall shape of a quarter box. Similarly, the tool 102.103 differs from the tool 2.3, because its molding cavity has generally the shape of a quarter parallelepiped.

La figure 8 illustre la surface dilatée 111 et la surface érodée 112, qui ont aussi des formes spécifiques en relation avec la pièce 104. La figure 8 illustre aussi un conduit d'alimentation ou carotte 107 pour l'injection de la matière thermoplastique.The figure 8 illustrates the expanded surface 111 and the eroded surface 112, which also have specific shapes in relation to the piece 104. The figure 8 also illustrates a supply conduit or core 107 for the injection of the thermoplastic material.

Les régions quasi-stationnaires 121 sont représentées à la figure 10. Les canaux 101 sont représentés à la figure 11. Les régions quasi-stationnaires 121 et donc les régions canaux 101, ont des formes plus complexes que les canaux 1. Pour cette raison, les canaux 101 sont à usiner par un procédé génératif, tel que le frittage sélectif par laser.The quasi-stationary regions 121 are represented at the figure 10 . The channels 101 are represented at figure 11 . The quasi-stationary regions 121 and therefore the channel regions 101, have more complex shapes than the channels 1. For this reason, the channels 101 are to be machined by a generative method, such as selective sintering by laser.

Le procédé illustré par les figures 7 à 11 diffère du procédé décrit ci-avant en relation avec les figures 1 à 6, car la géométrie des canaux 101 qui en résultent diffère de la géométrie de canaux 1.The process illustrated by the Figures 7 to 11 differs from the process described above in relation to the Figures 1 to 6 because the geometry of the resulting channels 101 differs from the channel geometry 1.

Des surfaces isothermes 123.1 et 123.2 correspondant à un niveau de température, est sélectionnée dans les régions quasi-stationnaires 121.Isothermal surfaces 123.1 and 123.2 corresponding to a temperature level, is selected in the quasi-stationary regions 121.

Ainsi, l'outillage 102.103 comprend des canaux 101 formés en mettant en oeuvre un procédé conforme à l'invention. Dans ce but, on peut utiliser un produit programme d'ordinateur qui met en oeuvre un algorithme réalisant un tel procédé.Thus, the tool 102.103 comprises channels 101 formed by implementing a method according to the invention. For this purpose, it is possible to use a computer program product which implements an algorithm implementing such a method.

Selon d'autres caractéristiques avantageuses mais facultatives, prises isolément ou selon toute combinaison techniquement admissible :

  • L'élément structurant pour réaliser la dilatation morphologique peut être autre qu'une sphère, par exemple un cube.
  • L'élément structurant pour réaliser l'érosion morphologique peut être autre qu'une sphère, par exemple un cube.
  • La surface de référence peut être définie par une opération morphologique différente de la dilatation, par exemple par un décalage de surface résultant d'une homothétie.
  • La surface définissant une gaine solidifiée peut être définie par une opération morphologique différente de l'érosion, par exemple par un décalage de surface résultant d'une homothétie.
According to other advantageous but optional features, taken alone or in any technically permissible combination:
  • The structuring element for performing the morphological dilation may be other than a sphere, for example a cube.
  • The structuring element for achieving morphological erosion may be other than a sphere, for example a cube.
  • The reference surface may be defined by a morphological operation different from the dilation, for example by a surface offset resulting from a homothety.
  • The surface defining a solidified sheath can be defined by a morphological operation different from erosion, for example by a surface offset resulting from a homothety.

Claims (13)

  1. A method for forming thermal regulation channels (1; 101) in a tooling (2.3; 102.103) intended to manufacture at least one part (4; 104) by molding a material in the tooling (2.3; 102.103), then by cooling the part (4; 104) by means of at least one heat transfer fluid circulating in thermal regulation channels (1; 101) to a predetermined stripping temperature, then by stripping the part (4; 104) out of the tooling (2.3; 102.103), the method comprising the steps of:
    - simulating the temperatures which are induced by heat transfer between the part (4; 104) and the tooling (2.3; 102.103) and between a moment of insertion of the material into the tooling (2.3; 102.103) and the moment of stripping of the part (4; 104);
    - determining a thermal field of the induced temperatures in a reference volume (17.4; 117.104) comprising the part (4; 104) and an intermediate volume extending between the outer surface of the part (4.1; 104.1) and a reference surface located in the tooling (2.3; 102.103);
    the method being characterized in that it further comprises the steps of:
    - locating in the thermal field regions called quasi-stationary regions (21; 121), in each of which the displacement of at least one isothermal surface (23, 23.1, 23.2, 23.3; 123, 123.1, 123.2) during a reference period has an amplitude less than a predetermined displacement limit, said reference period being comprised between the moment of insertion of the material into the tooling (2.3; 102.103) and the moment of stripping of the part (4; 104); and
    - inside of each quasi-stationary region (21; 121), selecting an isothermal surface (23, 23.1, 23.2, 23.3; 123, 123.1, 123.2) to define at least one portion (23.1, 23.2, 23.3; 123.1, 123.2) of a peripheral surface of a respective thermal regulation channel (1; 101).
  2. The method according to claim 1, wherein the step of simulating the temperatures induced by said heat transfer comprises the steps of:
    - carrying out a morphological expansion of the outer surface (4.1; 104.1) of the part (4; 104), so as to define an expanded surface forming said reference surface (11; 111);
    - carrying out a morphological erosion of the outer surface (4.1; 104.1) of the part (4; 104), so as to define an eroded surface (12; 112);
    - determining a temperature distribution of at least one heat transfer fluid on the reference surface (11; 111) such that:
    • on the one hand, the average of the simulated temperatures on the eroded surface (12; 112) is approximately equal to the predetermined stripping temperature at the end of the cooling; and
    • on the other hand, the simulated temperature at each point of the outer surface (4.1; 104.1) of the part (4; 104) is approximately equal to the average of the temperatures calculated on the outer surface (4.1; 104.1) of the part (4; 104) at the end of the cooling;
    and wherein the step of determining the thermal field comprises a calculation based on said temperature distribution on the reference surface (11; 111).
  3. The method according to claim 2, wherein the morphological erosion is carried out by means of a structuring member, for example a sphere, a dimension of which is substantially equal to a predetermined thickness of a solid sheath of the part (4; 104) in order to strip the part (4; 104).
  4. The method according to claim 1, wherein the step of simulating the temperatures induced by said heat transfer comprises the steps of:
    - carrying out a morphological expansion of the outer surface of the part, so as to define an expanded surface forming said reference surface;
    - determining a temperature distribution of at least one heat transfer fluid on the reference surface such that the simulated temperature at each point on the outer surface of the part is approximately equal to a predetermined temperature threshold on the outer surface of the part at the end of the cooling;
    and wherein the step of determining the thermal field comprises a calculation based on said temperature distribution on the reference surface.
  5. The method according to any of claims 2 to 4, wherein the morphological expansion is carried out by means of a structuring element, for example a sphere, a dimension of which is greater than a predetermined distance to ensure the mechanical strength of the tooling (2.3; 102.103) after formation of thermal regulation channels (1; 101).
  6. The method according to any of the preceding claims, further comprising a subsequent step consisting in completely forming a peripheral surface of a respective thermal regulation channel (1; 101) by closing said peripheral surface portion (23.1, 23.2, 23.3; 123.1, 123.2) when said peripheral surface portion (23.1, 23.2, 23.3; 123.1, 123.2) is partially delimited by the reference surface (11; 111).
  7. The method according to any of the preceding claims, wherein a respective heat transfer fluid temperature is associated to each thermal regulation channel (1; 101), when the selected isothermal surfaces (23, 23.1, 23.2, 23.3; 123, 123.1, 123.2) respectively inside distinct quasi-stationary regions (21; 121) correspond to different temperatures.
  8. The method according to claim 7, wherein the number of different heat transfer fluid temperatures which are associated to the thermal regulation channel (1; 101), is limited to the number of thermoregulatory circuits intended to supply the thermal regulation channels (1; 101) with heat transfer fluid.
  9. The method according to any of the preceding claims, wherein the shape of a respective thermal regulation channel (1; 101) is defined so as to minimize the pressure drops generated during the flows of the heat transfer fluid.
  10. The method according to any of the preceding claims, wherein each isothermal surface (23, 23.1, 23.2, 23.3; 123, 123.1, 123.2) is selected inside a respective quasi-stationary region (21; 121) so as to space apart the thermal regulation channels (1; 101) and the outer surface (4.1; 104.1) from the part (4; 104) such that the tooling (2.3; 102.103) resists to the thermomechanical stresses likely to be exerted during the manufacture of a part (4; 104).
  11. The method according to any of the preceding claims, wherein each isothermal surface (23, 23.1, 23.2, 23.3; 123, 123.1, 123.2) is selected inside a respective quasi-stationary region (21; 121) such that, between the moment of insertion of the material into the tooling (2.3; 102.103) and the moment of stripping of the part (4; 104), the temperature of a respective isothermal surface (23, 23.1, 23.2, 23.3; 123, 123.1, 123.2) is comprised in a predetermined range depending on the injected material.
  12. The method according to any of claims 2 to 5, wherein the temperature distribution of at least one heat transfer fluid on the reference surface (11; 111) is determined by means of an optimization algorithm involving the method called conjugate gradient method, preferably coupled with the technique called Lagrange multiplier technique.
  13. A computer program product, characterized in that it implements an algorithm carrying out a method according to any of claims 1 to 12.
EP12731553.9A 2011-06-10 2012-06-08 Method for forming channels in a tool and computer program product that performs such a method Active EP2720817B1 (en)

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FR1155099A FR2976201B1 (en) 2011-06-10 2011-06-10 METHOD FOR FORMING CHANNELS IN A TOOLING, TOOLING FORMED WITH SUCH A METHOD AND COMPUTER PROGRAM PRODUCT PROVIDING SUCH A METHOD
PCT/FR2012/051296 WO2012168669A2 (en) 2011-06-10 2012-06-08 Method for forming channels in a tool, tool thus formed and computer program product that performs such a method

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EP2720817B1 true EP2720817B1 (en) 2018-05-02

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