Soft tooling shaping method and use of an optimized molding unit

Abstract

A manufacturing method comprises the steps of producing by an automatic machine a three-dimensional mold made of a re-processable material comprising wax or thermoplastic material or thermoset material by a process comprising a heating step e.g. until the wax or thermoplastic material softens or melts and then solidifies; cooling the mold or form; applying, optionally under pressure, a polymeric material to the cooled mold or form, wherein the cooling step lowers the temperature of the mold or form so that the mold or form remains solid to shape said polymeric material as it cools from a hot condition to become a shaped object; heating the mold or form to soften or melt the mold or form material and automatically shaping a new mold or form.

Description

[0001] P7648PC01

[0002] “SOFT TOOLING SHAPING METHOD AND USE OF AN OPTIMIZED MOLDING UNIT”

[0003] DESCRIPTION

[0004] TECHNICAL FIELD

[0005] The present invention refers to a soft tooling shaping method for e.g. thermoforming or injection molding where the mold is of wax or a thermoplastic material and is reusable and reshapable. The invention further refers to a molding unit comprising a thermoformable foil holder, a heating source and a cooling source. The method and the molding unit are applicable to any process and product that requires a high level of customization and a high speed of production e.g. dental arches for teeth alignment, left / right insoles e.g. based on 3D scanner of the feet etc.

[0006] PRIOR ART

[0007] Manufacturing methods are either very fast albeit provide limited or null customization of the product or slower but with an increased level of customization.

[0008] Recently, acquisition of specific data of a user e.g. biometric data is common and a need is felt to customize a product based on such biometric data at a reasonable manufacturing speed. Furthermore, a constant need is felt to provide a manufacturing method that is sustainable e.g. improving the exploitation efficiency of materials.

[0009] For example, in the dental sector an issue that affects most people is related to malocclusions, wherein one or more teeth on a dental arch, or on both the dental arches, are not correctly aligned. In the case malocclusions are not significant, the patient may also continue to keep the teeth as they are aligned in the mouth, but in case malocclusions areP7648PC01

[0010] significant, the patients generally require treatments to bring the teeth affected to an aligned position. Therefore, several devices have been developed to correct teeth malocclusions, and in particular in the recent years have been developed teeth aligners shaped as a mask that be removably fitted on the dental arch wherein the malocclusions to be corrected is located. In particular, such devices are generally transparent and widely spreading thanks to the significant development of the additive manufacturing technologies that allow to produce complex shapes designed and customized for each patient. Moreover, such teeth aligners are provided as a sets of teeth aligners, wherein each one is shaped so as to move the teeth towards the correct alignment position but, since such treatment has to be gradually performed, each teeth aligner has to be fitted for a predefined period of time to gradually move the teeth towards an improved alignment position and then, a new teeth aligner has to be used to move the teeth from the previous improved alignment position to a further improved alignment position, and the treatment continues until the correct alignment is achieved. Such teeth aligners are manufactured by heating a thermoform foil, e.g. of thermoplastic material, which is then applied on a positive mold of the dental arch having the teeth in a desired alignment configuration. After the application of the thermoformable foil on the dental arch mold, such foil gets the shape of the surface of the mold e.g. a positive mold, thanks also to the application of a pressure or a depression that further keeps adhering such foil to the positive mold surface. Then, the thermoformed foil is transported to a cooling station, extracted from the mold, e.g. by trimming, and sent to the following working stations for finishing operations. As it can be understood, the production process of such teeth aligners requires many working stations in the factory, meaning that the factory space and the related costs increase, which causes therefore an increase in the final cost per unit of the parts produced. As it can be understood, having several working stations distributed over the factory requires many handling operations from one working station to the followingP7648PC01

[0011] one, which means a waste of time due to the parts handling and therefore a decrease in the factory production capacity.

[0012] It is therefore a felt need that of providing compact and multifunction solutions, capable of reducing the space required in the factory and at the same time to reduce handling time of the parts being produced, so as to decrease production costs per unit and to increase the overall factory production capacity.

[0013] SCOPE AND SUMMARY OF THE INVENTION

[0014] The present invention has the scope to satisfy at least part of the above mentioned needs, wherein such a scope is achieved through a molding unit according to claim 1.

[0015] The idea at the basis of the invention is to use a low melting point material for the mold to manufacture an object of ahigher temperature resistance material in order to make re-use of the mold material easy and simple. This is achieved by cooling the mold material in such a way that the mold keeps desired tolerances whilst the object polymeric material hardens. This can be achieved either by thermal inertia e.g. by freezing or cryogenic cooling of the mold prior to application of the softened or liquid material to be shaped or by controlling a heat exchange for extracting heat from the mold whilst the material is hardening. It is important to note that, in general, the lower the hardening temperature of a material, the higher the capability to re-cycle or re-use such material for the same or further scopes. In addition, often the object to be formed is of either a re-processable thermoset material (e.g., vitrimers) or of a thermoplastic material with high properties, which implies higher resistance to heat. Therefore, the method of the present invention is of a great importance because provides objects having high mechanical properties and at the same time implements easy recycling, in particular re-use, of the mold material.

[0016] According to a preferred embodiment of the present invention, an optimizedP7648PC01

[0017] molding unit configured to produce molded parts, preferably for dental applications such as teeth aligners for correcting malocclusions, is disclosed wherein a source of cooling power and a source of heat are kept at a fixed distance on from another and a moving element brings the cooled mold and the heated foil in contact in order to perform thermoforming. In particular, such a molding unit is designed and configured to perform different functions In particular, the molding unit according to such embodiment comprises a base, e.g. a table or a bench, on which a positive mold can be positioned to produce molded parts, preferably teeth aligners which can be removably fitted on the patient’s dental arch to correct malocclusions. Preferably, due to the complex shape of the molds which in case of dental applications are different form patient to patient, such molds can be manufactured by additive manufacturing technologies, e.g. thermoplastic polymers or wax-like reusable materials or re -processable thermoset material or reusable photopolymers, provided to the molding unit e.g. from a carousel of additive manufacturing technology machines downstream the molding unit. In this way, once the positive molds are used to produce the molded parts, e.g. teeth aligners, they can be reused to create a new positive mold, e.g. melting the mold again to bring the material to a liquid state for a new deposition or jetting process, without then having a waste of material used to produce the molds and improving the overall efficiency of the factory. According to the invention, the molding unit comprises a thermoformable foil holder on which in use a thermoformable foil, e.g. of thermoplastic material, is fixed so as to face the positive mold positioned on the base. According to an aspect of the present invention, such a thermoformable foil holder and the base are relatively movable to translation along a first direction, preferably vertical along a first axis. For example, the molding unit can comprise guides extending from the base to which the thermoformable foil holder is fixed so as to be movable to translation along such a first axis towards or away from the base. Therefore, to produce a molded part using the mold e.g. aP7648PC01

[0018] positive mold, the molding unit comprises a heating source and a cooling source, arranged oppositely with respect to the thermoformable foil holder so that the foil is suitably preheated for the subsequent thermoforming and the mold has a sufficient cold thermal energy reservoir, as explained above, to have the object material hardened. Under such a constructional configuration, the heating source is configured in use to heat, e.g. by irradiation, the thermoformable foil so as to increase its viscosity to make the foil deformable on the mold, while the cooling source is configured to cool down the mold below room temperature while the thermoformable foil is heated up. In this way, it is possible to exploit such a design configuration to perform several functions at the same time so as to produce the final parts in a reduced amount of time. According to a further aspect of the present invention, the thermoformable foil or the base is moved closer towards each other after the base being heated up by the heating source. In order not to colliding with the cooling source, the heating source and the cooling source are relatively movable to with respect to the thermoformable foil holder along a second direction transversely to the first direction, preferably along a second axis transversally to the first axis. In particular, from an extended position wherein the heating source faces the thermoformable foil holder and the cooling source faces the base, i.e. the positive mold, and a retracted position wherein the heating source and the cooling source are longitudinally spaced from the thermoformable foil holder so that such thermoformable foil holder is free to translate towards the base along the first axis. In this latter configuration, one of the heated thermoformable foil and the base is moved closer towards the other so that the thermoformable foil is applied to the positive mold and, when it happens, the positive mold is in a cooled state so as not to melt under the heat transmitted by such a thermoformable foil, i.e. the positive mold remains rigid maintaining the original morphology while the thermoformable foil is applied thereon. Therefore, the thermoformable foil is moved till touching the base to which partially attaches in order toP7648PC01

[0019] adhere to the positive mold surface. Moreover, in order to improve the adhesion of the thermoformable foil on the mold surface, the molding unit comprises a pressure chamber configured to apply a pressure or a depression. Preferably, such a pressure chamber can be mounted above the thermoformable foil holder, e.g. fixed to the guides on top of the heating source, e.g. so as to be movable to translation towards the base along the first axis. In particular, such a pressure chamber is configured to apply in use a positive pressure towards the base, in particular as the heating and cooling source are moved in a retracted position, e.g. by means of actuators, the thermoformable foil along with the pressure chamber are moved along the first axis towards the base so that while the foil is applied to the mold a positive pressure from the pressure chamber pushes the foil in contact with the mold surface. Alternatively, the pressure chamber can be arranged oppositely to the thermoformable foil holder with respect to the base to which it is fluidically connected to, e.g. through apertures or holes on the base. In this configuration, when the thermoformable foil is applied to the mold, part of such a thermoformable foil is also applied to the base covering the apertures or the holes on the base and, by applying a negative pressure through the pressure chamber, the air trapped in the deformed foil on the mold is sucked away so that the thermoformable foil is applied adhering to the positive mold surface, providing then the desired morphology to the final part.

[0020] According to an embodiment of the invention, a molding unit according to the above, receives an already shaped mold e.g. by another plant or by a supplier and, after the mold is used for shaping the object, the used mold is sent away, either within the same plant or to another plant, for softening by heating or melting and re-shaping of a new mold or form.P7648PC01

[0021] DESCRIPTION OF THE DRAWINGS

[0022] The constructional and functional features of the molding unit will be better understood from the detailed description that follows, wherein reference will be made to the attached figure that represent a preferred but not limitative embodiment of the present invention, wherein:

[0023] • Fig.l shows a non limiting flowchart of a method according to the present invention;

[0024] • Fig.2 shows a perspective view of a unit embodying some steps of the method in fig.

[0025] 1;

[0026] • Fig. 3 shows a schematic section view of a further unit embodying another step of the method in fig. 1; and

[0027] • Fig. 4 shows a second embodiment of a unit embodying some steps of the method in fig. 1.

[0028] DETAILED DESCRIPTION OF THE INVENTION

[0029] Figure 1 shows a flowchart of a method according to the present invention comprising the steps of forming 10 a mold by an automatic machine shaping a material having a first temperature behavior, cooling 20 the mold to prevent fast softening e.g. liquefaction during subsequent forming, applying 30 on or in the mold a hotter polymeric material either thermosetting or thermoplastic having a second temperature behavior in order to manufacture an object e.g. a teeth alignment mask or an insole and separating 40 the mold from the shaped object. The mold separated from the shaped object recycled e.g. is heated so as to be softened or liquified for being provided to the automatic machine and shaping a new mold. Temperature behavior is identified depending on the mold material as the softening temperature, glass transition temperature, solidification temperature or the like.

[0030] The material of the object have stronger temperature behavior compared to that ofP7648PC01

[0031] the mold and in order to preserve desired tolerances of the object, according to a first embodiment, cooling 20 comprises freezing or supercooling or cryogenic cooling i.e. cooling the mold exposing the latter to a fluid having at least 50°C less, preferably 75°C less even more preferably 100°C less than a temperature of application of the polymeric material on the mold in step 30. Given the temperature span and thermal inertia of the mold, the latter remains hard and preserves tolerances during forming of the object despite the starting temperature at which the shaping takes place in step 30 is high. Furthermore, the cooling step 20 terminates before applying the soft and / or hot material to be formed. Preferably it terminates 5 seconds or less, more preferably 2 seconds or less before application of the soft and hot material to be formed.

[0032] According to another embodiment that is either alternative to or combined with the above, the mold is manufactured in such a way as to include channels for the flow of a cooling fluid before step 30 and / or during step 30 in order to extract thermal power from the mold during step 30. According to a preferred embodiment, it is provided a control unit comprising a temperature sensor and a temperature sink e.g. a fluid tank kept at a desired low temperature wherein a flow of coolant fluid is controlled e.g. by varying a working parameter of a pump e.g. rotation speed and / or displacement of the pump, in order to keep a predefined temperature condition measured by the temperature sensor e.g. a pre-defined constant temperature during step 30.

[0033] Step 30 may be either a thermoforming of a polymeric sheet and / or film, as will be explained later, or by molding the polymeric material in a concave mold ad is the case for example in blow molding, injection molding or the like. Injection molding may comprise a step of applying to the mold, in particular a negative or concave mold, a first composition at room temperature where the temperature is increased by adding a second composition that initiates a chemical reaction generating heat and therefore reticulating a polymeric materialP7648PC01

[0034] generated from the reaction of the first and second composition within the cold or cooled mold.

[0035] During other processes e.g. thermoforming or preferably, in order to favor adhesion of the object material to the mold, pressure is applied to a surface of the object polymeric material opposed to the mold whilst the object material is hardening.

[0036] The material of the mold is either a re-processable thermoset material or a thermoplastic polymer or thermoplastic-like material or a wax, comprising both a natural wax or a paraffine wax, or a low melting point thermoplastic polymer, such as polyethylene wax (PE wax): a low-molecular-weight version of polyethylene. Has a similar melting behavior to paraffin but with better stability and hardness; polypropylene wax (PP wax): similar to PE wax but has a higher melting point and better chemical resistance; Fischer-Tropsch wax: a synthetic wax made from carbon monoxide and hydrogen (gas-to-liquid process). Harder and more temperature-resistant than natural waxes like paraffin; Montan wax: a natural fossilized wax, but structurally closer to some synthetic waxes; polyolefin wax blends: mixtures of low-molecular-weight polymers with wax-like properties.

[0037] According to an embodiment, in order to improve thermal flow out of the mold, the material of the mold is loaded with particles having a high thermal conductivity and a liquefaction temperature higher than that of the mold and of the object, in particular where channels are provided within the mold. Such particles preferably comprise boron nitride. The material of the particles shall chemically or physically react within its matrix at the temperature range of the process in figure 1.

[0038] According to a preferred embodiment, the automatic machine for shaping the mold is an additive manufacturing machine, in particular a jetting machine where droplets of liquid wax (or an equivalent polymer or a re -processable) are deposited by a moving head and / or a moving platform carrying the mold and harden immediately after to build precise 3DP7648PC01

[0039] shapes. This provides flexibility for both the mold surface to provide the object and to the construction of through channels within the mold to receiving the cooling fluid.

[0040] Preferably, re-process of the mold material is provided more than one step of the manufacturing method e.g. a quantity of mold material for re-use is collected after forming of the mold and comprises the support material e.g. for shaping an undercut..

[0041] Furthermore, forming of the mold comprises preferably a step of quality check of the mold shaped by the automatic machine e.g. tolerance check by measuring or scanning the mold and compare the output of the tolerance check with desired values. In case the mold does not comply with the quality check, it is re-used.

[0042] Preferably, after step 30, the method of the invention further provides a trimming step T e.g. a laser trimming, to separate from the object unwanted portion of polymeric material.

[0043] Figure 3 shows a preferred embodiment of a mold material tank for re-use. In particular, mold material may have water or other impurities and, after entering the tank, is heated so that heavier liquids e.g. water fall at the bottom of the tank and gaseous material is accumulated at the top of the tank. A scraper pr the like displaces the free surface of the liquid mold material in the tank, which is decontaminated, above a separating wall W in a volume V where decontaminated wax is accumulated. A new mold is formed collecting mold material from such a volume.

[0044] According to a preferred but not limitative embodiment of the present invention, a molding unit M according to fig. 2 is provided to automatically perform the cooling step and the object material hardening step by comprising a foil holder relatively movable with respect to a cooling source and a heating source and with respect to the mold, the cooling source and the heating source being at a fixed relative position one from the other. According to an embodiment, this is achieved according to the following layout configured to produceP7648PC01

[0045] molded parts e.g. for dental applications, such as teeth aligners, but such a molding unit can be adopted to produce molded parts also for other applications not described therein. In particular, in Fig.2 is shown as a whole a molding unit M configured to produce molded parts, preferably teeth aligners, starting from a thermoform foil, preferably of a polymeric material which is solid at room temperature and softens or liquifies at a higher temperature than that at which the mold material soften or liquifies. In particular, the molding unit M comprises a base 1, e.g. a table or a bench, having a portion on which a mold, e.g. of a dental arch (not visible in figure) can be positioned so as to perform the operations to mold a teeth aligner. Moreover, such a mold of a dental arch is generally manufactured starting from a scanned tridimensional model of a region of interest of an individual e.g. the dental arch The production of such molds is usually performed using additive technologies as it is possible to achieve a significant level of customization and complex shapes specifically designed based on patient’s dental arch morphology, even if other production techniques may be used, e.g. by material removal. As shown in Fig.2, the molding unit M comprises a thermoformable foil holder 2 which is arranged above the base 1 extending horizontally, being such a thermoformable foil holder vertically hollow so as to define a frame to which a thermoform foil, e.g. of thermoplastic material, can be fixed facing the base. Moreover, in order to vertically support the thermoformable foil holder 2, the molding unit M comprises guides 3 which are rigidly fixed to the base 1 and longitudinally extending upwardly, preferably perpendicularly, from said base. Furthermore, the thermoformable foil holder 2 is fixed to the guides 3 so as to be movable with respect to the base along a first direction Al, preferably along a first axis, e.g. through a belt transmission which is powered by an electric motor onboard the molding unit. In this way, the thermoformable foil holder 2 can vertically move towards the base or away from the base. As an alternative or in addition, the base 1 can be vertically movable with respect to the thermoformable foil holder 2 which may remain fixedP7648PC01

[0046] in a predefined position with the base moving towards or away from the thermoformable foil holder. According to an aspect of the present invention, the molding unit M comprises a heating source 4 and a cooling source 5 arranged vertically oppositely with respect to the thermoformable foil holder 2. Preferably, the heating source 4 is an infrared heater or a heat lamp or another heater to have the foil ready for thermoforming, and it is vertically spaced from the thermoformable foil holder 2 in order to provide in use heat by irradiation on the thermoformable foil surface. Furthermore, in order to arrange the heating source and the cooling source vertically oppositely with respect to the thermoformable foil holder 2, the molding unit M comprises a support structure 6, preferably with a ‘C’ shape, having opposite arms 7 extending horizontally that are configured to rigidly fix the heating source 4 on one side, and the cooling source on the other side. In particular, the heating source is rigidly fixed to the corresponding arm in order not to obstruct the exposure of such a heating source towards the thermoformable foil holder 2 so that in use the heat can be uniformly provided to the thermoform foil. Therefore, the arm of the support structure 6 holding the heating source 4 is opposite arranged with respect to the heat emission. The cooling source 5 instead is rigidly fixed to the corresponding arm in order not to obstruct the exposure of such a cooling source towards the base 1 so that in use the cooling can be uniformly provided to the base, and consequently to the mold. According to a further aspect of the present invention, the heating source 4 and the cooling source 5 are movable with respect to the thermoformable foil holder 2 and, consequently, with respect to the base 1. In particular, such a heating source and a cooling source are movable along a second direction A2, preferably a second axis, transversely to the first direction Al, and preferably perpendicular, from an extended position, wherein the heating source 4 faces the thermoformable foil holder 2 so as to provide in use heat to the thermoformable foil to make it deformable, and the cooling source 5 faces the base 1 so as to provide cooling to the mold, to a retractedP7648PC01

[0047] position wherein the heating source and the cooling source are longitudinally spaced from the thermoformable foil holder 2 so that such thermoformable foil holder is vertically free to translation along the first direction Al towards the base 1, e.g. along the first axis. Furthermore, since the heating source and the cooling source 4, 5 are rigidly fixed to the support structure 6, the movement of such a support structure causes a rigid movement of the heating and cooling source, in particular a rigid translation transversely, and preferably perpendicularly, with respect to direction of movement of the thermoformable foil holder 2, i.e. a vertical translation towards or away from the base 1. In particular, the support structure 6 movement can be driven by one or more actuators 8, preferably connected to the base or to another frame structure, which in use are actuated so as to extend and driving the heating source and the cooling source to the extracted position. Preferably, each one of the heating source and the cooling source can have its own support structure 6 not connected to the support structure of the other, so that it is possible to control the movement of the heating source 4 independently from the movement of the cooling source 5, e.g. an actuator can be provided for each one of the heating source and the cooling source. Preferably, the molding unit M can be also configured to have the heating and cooling source 4, 5 fixed and the thermoformable foil holder 2 movable along the second direction A2, e.g. along the second axis, from an extended to a retracted position. Moreover, according to the preferred embodiment shown in Fig. 2, it is firstly necessary to drive the heating source 4 and the cooling source 5 in an extracted position, with the thermoformable foil holder 2 bearing a thermoformable foil thereon and the mold positioned on the base 1. When reached such a configuration, the heating source 4 is powered so has to transmit the heat by irradiation to the thermoformable foil which causes a decrease of the viscosity of the material of the thermoformable foil with a consequent increase of the deformability thereof. Meanwhile the thermoformable foil is heated up by the heating source 4, the cooling source 5 is powered toP7648PC01

[0048] cool down the mold below room temperature. Therefore, the heating and the cooling sources 4, 5 are driven in a retracted position so as to the thermoformable foil can be moved towards the mold on the base. In particular, when the thermoformable foil reaches a level of viscosity so as to be deformed over the mold of the dental arch, and such a mold is cooled down so as to be rigid enough to maintain the original shape and tolerances when gets in contact with the heated foil, both the heating device 4 and the cooling device 5 are driven to a retracted position. In particular, since the thermoformable foil holder 2 is vertically interposed between the heating and the cooling source 4, 5 when these latter are in the extended position, its stroke is vertically limited in between such a heating and cooling sources. When the heating and the cooling devices 4, 5 are driven in the retracted position instead, the thermoformable foil holder 2 is able to move freely towards the base 1 to bring the heated thermoformable foil in contact with the mold to shape an object such as a teeth aligner. In particular, the heated thermoformable foil is driven till it reaches the base 1. Since the positive mold is abutting on the base and vertically extends from such a base, when the thermoformable foil is moved towards the base it gets in contact first with the positive mold surface, on which the thermoformable foil deforms following the profile of the surface of the mold. Moreover, due to the contact with the cooled surface of the mold which is cooled so as not to melt or soften when getting in contact with the heated thermoform foil, the thermoformable foil solidifies in the deformed shape given by the surface profile of the mold. Moreover, in order to improve the adhesion of the thermoformable foil on the mold surface so has to provide a molded part having a shape as much as possible representative of the positive mold morphology, the molding unit M comprises a pressure chamber 9. Such a pressure chamber is arranged above the thermoformable foil holder so as to provide a positive or negative or both pressure towards the base 1 so as to favor the adhesion of the thermoformable foil on the mold surface. Preferably, such a pressure chamber is arrangedP7648PC01

[0049] vertically oppositely to the base 1 with respect to the heating source 4, e.g. mounted on the guides 3 so as to be movable along the first direction Al to move towards the base 1 when the heating and the cooling source 4, 5 are in a retracted position. Alternatively, the pressure chamber 9 can be arranged oppositely to the thermoformable foil holder with respect to the base 1 to which is fluidically connected. For example, the base 1 can be apertured or can have holes so as to define a fluidic connection between the pressure chamber 9 and such a base. In this way, when the thermoformable sheet, foil or film is applied to the mold, part of such a thermoformable foil is also applied to the base covering the apertures or the holes on the base and, by applying a negative pressure through the pressure chamber, the thermoformable foil is applied to the mold surface providing then the desired morphology of the object. When the application of the thermoformable foil is completed, the molded object is then delivered to a next working station for finishing operations, e.g. trimming of the surrounding molded thermoformable foil that is not necessary on the final part.

[0050] According to not-shown embodiment, the foil holder pivots between a first angular position wherein the foil is angularly distanced from the base of the mold and a heating head is selectively movable e.g. slidable to face the foil and to be away of the foil without; and a second angular position wherein the foil holder, after rotation faces the base and, in use, applies to the heated foil the force to adhere to the mold. Optionally a pressure chamber is movable on and away the base in order to apply a positive and / or negative pressure so as to ensure full adherence of the heated foil on the mold. For example, heating head and the base are aside and the foil holder pivots of about 180° along a curved direction.

[0051] According to a preferred embodiment of figure 2, a heat shield or screen is provided between the heating head and the cooling head so that the cooling source and the mold are thermally isolated from irradiation and the foil is thermally isolated from cold. This improves efficiency of cooling and heating.P7648PC01

[0052] According to a not shown embodiment, the base is cooled in combination or alternative to the cooling head and comprises holes to fluidically connected to the channels of the mold so as to adduct a cooling fluid. Preferably, the base comprises one or more plugs, to define such holes and the mold is either formed embedding such plugs or is mounted on such plugs in a softened state in order to provide fluidic connection with the cooling fluid circuit of the base.

[0053] According to figure 4 a device to implement the method of the invention comprises a movable heater 100, preferably a linearly movable heater, and a transporting device 101 for the foil of the polymeric material, wherein the transporting device 101 and the heater 100 have a common heating area where the foil carried by transporting device 101 is heated by transporting device 101. Preferably, according to figure 4, heater 100 is above the foil during heating in the heating area. Heater 100 is movable in a further position away from the heating area e.g. in order to clear the way so that a new undeformed foil is placed on transporting device 101 to start a new working cycle. Transporting device 101 is configured to transport the heated foil in a forming station where the foil shall be formed on a mold. According to the embodiment in figure 4, transporting device is a shuttle travelling on guides from the heating area to the forming station.

[0054] According to the embodiment of Figure 4 hardening by cooling on mold is operated in a station that is not shown and placed on the toggle mechanism e.g. by a shuttle or the like.

[0055] Figure 4 shows that the cooled mold, i.e. the mold hardened by cooling, is carried on a toggle mechanism 102 having a retracted position away from forming station and an advanced position where the hardened mold interferes with the foil so that the latter is formed. Preferably, forming is aided by pressure that is positive on the foil side to push on the mold. The motion between the away position on the forming station of the togglingP7648PC01

[0056] mechanism 102 is preferably linear and perpendicular to the undeformed foil on transporting device 101.

[0057] Preferably, a sagging sensor 103 detects when a foil is on transporting device 100 is ready for heating.

Claims

P7648PC01CLAIMS1. A manufacturing method comprising the steps of:Producing by an automatic machine a three-dimensional mold made of a re -processable material comprising wax or thermoplastic material or thermoset material by a process comprising a heating step e.g. until the wax or thermoplastic material softens or melts and then solidifiesCooling the mold or formApplying, optionally under pressure, a polymeric material to the cooled mold or form, wherein the cooling step lowers the temperature of the mold or form so that the mold or form remains solid to shape said polymeric material as it cools from a hot condition to become a shaped object;Heating the mold or form to soften or melt the mold or form material and automatically shaping a new mold or form.

2. The method of claim 1, wherein the automatic machine is an additive manufacturing machine, preferably a material jetting 3D printing machine3. The method according to any of the preceding claims, wherein the cooling is either freezing or supercooling or cryogenic cooling.

4. The method according to any of the preceding claims, wherein the step of producing comprises the step of forming at least one through channel within the mold or form and the step of cooling includes the step of adducting a cooling fluid within the at least one through channel e.g. when the object material is hardening.

5. The method according to any of the preceding claims, wherein the mold material is such to soften at a lower temperature than that at which the object material softens.

6. The method according to any of the preceding claims, wherein the re-heated mold material in a softened or liquid state is separated from another liquid or gas when at aP7648PC01softened state so as to be purified before shaping of the new mold or form.

7. Use of a molding unit (M) within a method according to any of the preceding claims, to implement said applying step, the molding unit (M) comprising:— a base (1) for a mold or form of a wax or thermoplastic material;— a thermoformable foil or sheet or film holder (2) relatively movable along a first direction (Al) with respect to the base (1);— a heating source (4) and preferably a cooling source (5), at least the heating source (4) being movable with respect to the first direction (Al) along a second direction (A2) different from e.g. intersecting the first direction (Al) from a first position wherein the heating source (4) faces the holder (2), and a second position wherein the heating source does not interfere with the first direction (Al) so that the holder (2) and the base (1) are relatively movable along the first direction (Al).

8. Use of the molding unit according to claim 7, wherein the base (1) comprises a plurality of holes for connection of the mold to a cooling circuit when the mold rests on the base.

9. Use of the molding unit according to claim 8, wherein the base (1) comprises one or more plugs at least one of which defines one of said holes, so that the mold, when resting on said base (1) embeds the plug and the latter is fluidically connected with a channel of the mold to adduct a coolant.

10. Use of the molding unit according to any of claims 7 to 9, wherein the unit further comprises a pressure device (9) configured to apply in use a positive or negative or both pressure on the heated foil to adhere to the cooled mold.

11. Use of the molding unit according to any of claims 7 to 10, wherein the unit comprises a thermal shield to thermally insulate the base, and optionally cooling head, and the heating head from one another.

12. A manufacturing method comprising the steps of:P7648PC01Receiving a three-dimensional mold made of a re -processable material comprising wax or thermoplastic material or thermoset material by an automatic machine functioning according to process comprising a heating step e.g. until the wax or thermoplastic material softens or melts and then solidifiesCooling the mold or formApplying, optionally under pressure, a polymeric material to the cooled mold or form, wherein the cooling step lowers the temperature of the mold or form so that the mold or form remains solid to shape said polymeric material as it cools from a hot condition to become a shaped object, wherein the step of applying is performed by a molding unit (M) comprising:— a base (1) for a mold or form of a wax or thermoplastic material;— a thermoformable foil or film or sheet holder (2) relatively movable along a first direction (Al) with respect to the base (1);— a heating source (4) and preferably a cooling source (5), at least the heating source (4) being movable with respect to the first direction (Al) along a second direction (A2) different from e.g. intersecting the first direction (Al) from a first position wherein the heating source (4) faces the holder (2), and a second position wherein the heating source e does not interfere with the first direction (Al) so that the holder (2) and the base (1) are relatively movable along the first direction (Al);Sending the used mold to a heating station where the mold or form is softened or melt for automatically shaping a new mold or form.

13. Use of a molding unit within a method according to any of claims 1-6, to implement said applying step, the molding unit (M) comprising:a toggle mechanism (102) for a mold or form of a wax or thermoplastic material; a thermoformable foil or sheet or film holder (101) relatively movable along a firstP7648PC01direction (Al) with respect to the toggle mechanism (102);— a heating source (100), at least the heating source (100) being movable from a first position wherein the heating source (100) faces a foil or sheet on the holder (101), and a second position wherein the heating source is away from the foil or sheet; wherein the toggle mechanism has a retracted position to receive the cooled form or mold and an advanced position so that the cooled mold receives the heated foil.

14. Use of a molding unit according to any of claims 7 to 13, wherein the molding unit comprises a sagging sensor (103) configured to detect whether the foil or sheet is ready for thermoforming.

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