Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/10—Processes of additive manufacturing
  • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
  • B29C64/118—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using filamentary material being melted, e.g. fused deposition modelling [FDM]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/10—Processes of additive manufacturing
  • B29C64/188—Processes of additive manufacturing involving additional operations performed on the added layers, e.g. smoothing, grinding or thickness control
  • B29C64/194—Processes of additive manufacturing involving additional operations performed on the added layers, e.g. smoothing, grinding or thickness control during lay-up
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y10/00—Processes of additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y40/00—Auxiliary operations or equipment, e.g. for material handling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/30—Auxiliary operations or equipment
  • B29C64/364—Conditioning of environment

Definitions

• the subject of the invention is a process and a system for manufacturing a decorative object.
• the invention relates in particular, but not exclusively, to the technical field of temporary or permanent light decorations, and more specifically to light decorations located outdoors, such as those traditionally installed for parties or other events.
• the invention can also find many other applications, for example in the field of advertising decorations or for the animation of commercial windows.
• Patent documents FR3075313 and FR3069800 are known for manufacturing processes for a decorative object from at least a first layer of a hot-extruded bead of a composition based polymer. This type of process is particularly advantageous insofar as it makes it possible to obtain an object whose shape is complex, in particular an object in volume and/or with one or more curved contours.
• composition described in FR3075313 and FR3069800 is based on polymers or copolymers of the ABS (Acrylonitrile Butadiene Styrene), ASA (Acrylonitrile Styrene Acrylate) or SMMA (Styrene Methyl Methacrylate) type, these materials being used for their good impact resistance and aging.
• ABS Adiene Styrene
• ASA Acrylonitrile Styrene Acrylate
• SMMA Styrene Methyl Methacrylate
• an objective of the invention is to propose a method of manufacturing a decorative object from at least a first layer of an extruded cord, but whose impact on our environment is reduced, while allowing to get a decorative item which is of a beautiful aesthetic appearance, stable and sufficiently resistant from a mechanical, chemical and thermal point of view, taking into account the degraded climatic conditions in which the object can be used. Indeed, this object is intended to be preferably installed outside, whatever the environmental conditions.
• Another objective of the invention consists in proposing an economical and reliable manufacturing process, that is to say allowing, in an ambient environment, easy industrialization and perfect reproducibility of the object as many times as it is desired.
• the solution proposed by the invention is a method for manufacturing a decorative object from at least a first layer of a hot-extruded bead of a polymer-based composition, comprising a step of passing a polymer-based composition in an extrusion die from a supply inlet of said composition to an extrusion head from which the extruded bead emerges, in the ambient environment, the first layer of extruded bead being deposited on a receiving medium.
• Patent document WO2020016114 discloses a process for applying a material containing a fusible polymer, but this process applies to hot melts, this document making no mention or disclosing any example of a polymer-based composition comprising recycled polyethylene terephthalate , or a mixture of recycled polyethylene terephthalate and non-recycled polyethylene terephthalate.
• the manufacturing process is automated in such a way as to eliminate, or at least limit, the workforce.
• cooling temperature in relation to the receiving support means the fact that the latter has this temperature at its upper surface, i.e. the surface in contact (or likely to be in contact) with the extruded cord .
• the expression “decorative object” means an object whose purpose is the aesthetic decoration of a place, interior or exterior.
• this decorative object can be associated with one or more other visual elements such as for example garlands or lights and in this case the decorative object also serves as a support for these elements associated with the decorative object.
• the expression "mixture of recycled polyethylene terephthalate (PET) and non-recycled polyethylene terephthalate” means a mixture based on recycled polyethylene terephthalate incorporating or including an addition of non-recycled polyethylene terephthalate, that is to say not resulting from a recycling process, originating from a direct synthesis of polyethylene terephthalate.
• This non-recycled PET may consist of so-called “virgin” PET or PET-G, modified polyethylene terephthalate glycol (“polyethylene terephthalate glycol-modified”) and this non-recycled PET may contain all or part of virgin PET and/or PET-G.
• the non-recycled PET can itself consist of a PET mixture, typically a mixture of PET and PET-G, or consist entirely of PET-G.
• ambient temperature means a temperature between 15°C and 30°C for a pressure of approximately 1 atmosphere (10 5 Pascal).
• the cooling temperature of the receiving support is chosen so that the cooling rate of the first layer of extruded cord is between 250° C./min and 350° C./min.
• the reception support is made of a material chosen from the following family: aluminum, aluminum alloy, copper, copper alloy.
• the receiving medium is cooled to a temperature between -10°C and +10°C.
• the polymer-based composition has at least 99% by mass of polyethylene terephthalate and the following residual quantities: at most 50 ppm of polyvinyl chloride, at most 100 ppm of water, and at most 30 ppm of polyethylene.
• the polymer-based composition has at least 50% by weight of recycled polyethylene terephthalate.
• the decorative object comprises a plurality of layers of extruded cords, each successive layer, after the first layer of extruded cord, then forming the support for receiving the next layer of extruded cord.
• the extruded cord is cooled by blowing a gas so as to force the cooling of said cord by convection, said gas being blown at a temperature lower than or equal to the temperature of the ambient medium.
• the decorative object comprises a plurality of layers of extruded cords, each successive layer, after the first layer of extruded cord being cooled by blowing a gas so as to force the cooling of said cord by convection, said gas being blown at a temperature less than or equal to the temperature of the ambient medium.
• the gas temperature is chosen so that the cooling rate of the extruded bead is between 250° C./min and 350° C./min.
• the temperature of the gas is between -10°C and +10°C.
• the extrusion of the bead and the blowing of the gas are carried out concomitantly during the movement of the extrusion head (51) along the path.
• the method comprises a step consisting in securing one or more gas blowing nozzles to the extrusion head.
• the method comprises a step consisting in securing one or more gas blowing nozzles to a displacement means, which displacement means is controlled so that the nozzle or nozzles move at the same time as the extrusion head and along the same trajectory.
• the method comprises the steps of: - securing the extrusion head to a robotic manipulation arm; - control the arm so as to move the extrusion head along a trajectory so that the extruded bead forms a decorative object having at least one curved outline.
• the method comprises the steps of: - securing the receiving support to a moving means; - Control the moving means so as to move the receiving support along a trajectory so that the extruded cord forms a decorative object having at least one curved outline.
• Another aspect of the invention relates to a system for manufacturing a decorative object from at least a first layer of a hot-extruded bead of a polymer-based composition, comprising:
• an extrusion die having at one end a feed inlet and at the other end an extrusion head, said die being fed with at least one outgoing polymer-based composition, in an ambient medium, in the form of a bead extruded by the extrusion head,
• the polymer-based composition comprises recycled polyethylene terephthalate, or a mixture of recycled polyethylene terephthalate and non-recycled polyethylene terephthalate,
• the temperature of the extruded cord, at the exit of the extrusion head is between 200°C and 300°C
• the reception support incorporates cooling means so as to force the cooling of the first layer of bead extruded by conduction, the cooling temperature of said support being lower than the temperature of the ambient medium.
• the system comprises means for blowing a gas onto the extruded bead so as to force the cooling of said bead by convection, said gas being blown at a temperature less than or equal to the temperature of the ambient medium.
• FIG. 1 is a schematic view of a decorative object capable of being manufactured with the method and the system according to the invention.
• FIG. 2 is a side view of a manufacturing system in accordance with the present invention.
• FIG. 3 is an enlargement of part A present in figure 2, showing in particular the end of the extrusion head (the gas blowing device being represented) and the receiving support.
• FIG. 4 is a top view of the system visible in Figure 2 (the gas blowing device being shown).
• FIG. 5 is another side view of the system visible in Figure 2 (the gas blower being shown).
• FIG. 6 is a perspective view of the system visible in Figure 2 (the gas blower device not being shown for clarity).
• FIG. 7 is an alternative embodiment of a manufacturing system according to the present invention.
• the method and the system that is the subject of the invention make it possible to produce decorative objects, in particular supports for decorations such as decorations luminous.
• These decorations each comprise a rigid object forming a support frame, and on which is installed one or more light garlands.
• the decorative object 1 consists of a stylized snowflake 2 installed on a volute 3.
• its length is between 50 centimeters (cm) and two meters while its width is between 20 cm and one meter.
• a feature of the present invention lies in the fact that such an object is formed of at least one layer of extruded cord, possibly a plurality of layers of extruded cords and these extruded cords all have a substantially identical thickness, between 3mm and 10mm.
• This object 1 can be attached to a cable or fixed to a pole or a wall for an outdoor installation, for example in a street or on the facade of a monument, or even inside a dwelling.
• One or more light garlands can be attached to this object 1.
• the garland can be attached using quick fasteners, such as Rislan® type clamps.
• object 1 is obtained by hot extrusion of a polymer-based composition.
• This composition comprises recycled polyethylene terephthalate (PET), or a mixture of recycled PET and non-recycled PET.
• Recycled PET comes from recycling bottles in the following successive stages:
• regenerators sometimes carry out a final purification step by optical sorting. For this, we use different detection processes and cameras that will identify the last elements undesirable among PET flakes.
• a blowing system then separates the PET flakes from other types of plastic.
• PET flakes There are different types of PET flakes: those in clear PET (from transparent or light blue bottles) and those in dark PET (from dark blue, green or colored bottles).
• the recycled PET preferably comes from dark PET flakes.
• the PET flakes will then begin an extrusion phase. It consists of melting the flakes at a temperature of around 280°C to produce rods which will be cooled in water and then cut to form granules. There are clear pellets from light PET and colored pellets from dark PET. The PET granules are then purified, for example by polycondensation.
• a mixture of recycled PET and (non-recycled) PET has at least 50% by weight of recycled PET, preferably at least 70% by weight of recycled PET.
• the composition has at least 99% by weight of PET and the following residual amounts:
• the remaining less than 1% by weight of the polymer composition may consist of a polyester such as for example a PLA (polymer of polylactic acid) or a PCL (Polycaprolactone).
• a polyester such as for example a PLA (polymer of polylactic acid) or a PCL (Polycaprolactone).
• the water content is determined by Karl Fischer titration while the PVC (Polyvinyl chloride) and PE (Polyethylene) content can be obtained by various methods known to those skilled in the art and which give identical results. or quasi-identical, in particular ASTM D5991-17 (process C or D) of 2017 for PVC and ISO 11542-1 of 2001 or ISO 1133-1 of 2011 for PE.
• PVC Polyvinyl chloride
• PE Polyethylene
• the residual quantities also have at most five (5) ppm of metals.
• metal is understood to mean essentially, but not exclusively, metal hydroxides such as, for example, a sodium hydroxide, potassium hydroxide or else a calcium hydroxide. The applicant was able to determine that beyond a certain quantity of metals, the latter have a negative impact on the mechanical and/or physico-chemical properties of the manufactured object.
• the residual quantities also have at most ten (10) ppm of polyacrylonitrile (PAN).
• PAN polyacrylonitrile
• This PAN is a component which is likely to be found in greater or lesser quantities in recycled PET.
• the applicant has demonstrated a negative impact of this PAN, when present beyond a certain quantity, on the mechanical and/or physico-chemical properties of the manufactured object.
• the aforesaid composition is mixed with at least one additive to form the extruded beads, said additive being present in the "polymer-based composition - additive" mixture at a level of at most 40 % by weight of said mixture.
• the additive is present in the "polymer-based composition - additive" mixture in the amount of at most 10% by weight of said mixture, preferably at most 5% by weight of said mixture.
• the additive consists of plasticizers, adhesion promoters, UV stabilizers/absorbers, antioxidants, flame retardants, pigments/dyes/brighteners and/or fillers.
• plasticizers can refer to a plurality of plasticizers of the same composition and nature/chemical family.
• This same expression in the plural can also refer to a plurality of components - from a chemical point of view, the component is not unique - different, by their composition as well as their nature/chemical family, all belonging to the same category of additives, for example to the family of plasticizing additives.
• ABS Acrylonitrile butadiene styrene
• PC Polycarbonate
• PA66 Polyamide 6-6
• PMMA Poly(methyl methacrylate)
• PVC Polyvinyl chloride
• PE Polyethylene
• H2O water.
• MPa means Mega Pascal and KJ.nr 2 means kilo Joule per square meter.
• the latter may comprise a certain number(s) of additive(s) or component(s) intended to confer additional particular properties and/or to improve the intrinsic properties of the composition.
• the polymer-based composition according to the invention can be mixed with at least one additive so as to form a final mixture, exhibiting property(ies) and/or or additional function(s).
• this additive is only optionally present given the excellent intrinsic properties of the composition based on recycled PET.
• this composition has excellent mechanical properties, so it may be desired, or even necessary, to improve in particular its flame-retardant properties or even resistance to aging due to solar rays.
• Plasticizers may be added to the composition in order to facilitate the implementation and improve the productivity of said composition. Mention may be made, as examples, of aromatic or naphthalene paraffinic mineral oils which also make it possible to improve the adhesion power of the composition according to the invention. Mention may also be made, as plasticizer, of phthalates, azelates, adipates, ticresyl phosphate.
• Adhesion promoters although not necessary, can advantageously be added in order to improve the adhesion power of the composition when this must be particularly high.
• the decorative object obtained according to the invention is intended to be used as such, without being associated with an ancillary object such as an aluminum frame or another polymer material. Nevertheless, in the latter case in particular, the use of adhesion promoters is useful, even necessary, in order to ensure perfect cohesion, bonding or association of the decorative object and another polymer-based element, created independently of said object.
• the adhesion promoter is a non-polymeric ingredient; it can be organic, crystalline, mineral and more preferably semi-mineral semi-organic.
• organic titanates or silanes such as, for example, monoalkyl titanates, trichlorosilanes and trialkoxysilanes, trialcooxysilanes.
• organic titanates or silanes such as, for example, monoalkyl titanates, trichlorosilanes and trialkoxysilanes, trialcooxysilanes.
• trialcooxysilanes containing an epoxy, vinyl and amine group will be used.
• UV (Ultra-Violet) radiation is likely to cause a slight yellowing of the polymer-based composition used so that UV stabilizers and UV absorbers such as benzotriazole, benzophenone and other hindered amines can advantageously be added in order to ensure the transparency or an invariant coloration of the decorative object throughout its lifetime.
• UV stabilizers and UV absorbers such as benzotriazole, benzophenone and other hindered amines can advantageously be added in order to ensure the transparency or an invariant coloration of the decorative object throughout its lifetime.
• UV stabilizers and UV absorbers such as benzotriazole, benzophenone and other hindered amines can advantageously be added in order to ensure the transparency or an invariant coloration of the decorative object throughout its lifetime.
• UV stabilizers and UV absorbers such as benzotriazole, benzophenone and other hindered amines
• These compounds may for example be based on benzophenone or benzotriazole. We can them add in
• Antioxidants can also be added to limit yellowing during the manufacture and use of the decorative object, such as phosphorus compounds (phosphonites and/or phosphites) and hindered phenolics. These antioxidants can be added in amounts of less than 10% by mass of the total mass of the composition and preferably from 0.1 to 5%.
• Flame retardants may also be added. These agents can be halogenated or non-halogenated, the use of the latter being recommended, or even mandatory, depending on the country. Among the halogenated agents, mention may be made of brominated products such as polybrominated biphenyls or phosphobrominated compounds.
• phosphorus-based additives such as phosphates, phosphonates and polyphosphonates, nitrogenous organophosphates, phosphines and phosphine oxide, antimony oxide, polyphosphate, phosphinate or pyrophosphate, melamine cyanurate, pentaerythritol, zeolites, red phosphorus as well as mixtures of these agents.
• phosphines and phosphine oxides mention may be made of triphenylphosphine oxide, triphenylphosphine with melamine phosphate or 1,4 diisobutyl-2,3,4,5,6-tetrahydroxy-1,4-diphosphacyclohexane 1, 4-dioxide.
• phosphonates and polyphosphonates mention may be made of cyclic phosphonate, polysulfonyldiphenylene phenylbosphonate, polysulfonyldiphenylene thophenylphosphonate, syrupphosphonate or polyphosphonate with biphenyl bridges.
• nitrogenous organophosphates mention may be made of melamine phosphate or pyrophosphate, melamine polyphosphate, triphenylphosphine sulfide, diphosphonic acid.
• melamine phosphate or pyrophosphate mention may be made of bisphenol A and its derivatives, tribisphenylphosphate or resorcinol bis(diphenylphosphate).
• the composition may comprise these agents in proportions ranging from 0.5% to 25% relative to the total mass of the polymer-based composition mixture according to the invention - additive(s), in this case flame.
• pigments such as, for example, titanium dioxide, coloring or brightening compounds in proportions of up to one maximum of 10% relative to the total mass of the "polymer-based composition - additive(s)" mixture, in this case of pigments / dyes / brighteners.
• Fillers in particular of the mineral type, can also be added to improve the thermomechanical behavior of the composition.
• Figures 2 to 7 attempt to show the elements of a system for manufacturing a decorative object from at least one extruded bead of the aforementioned polymer-based composition. These elements allow the implementation of the method according to the invention so that a characteristic linked to the system finds application to the method, and vice versa.
• an extrusion die 50 heats it. A bead then leaves the extrusion head 51 in an ambient environment. Since the extrusion takes place in an ambient environment and not in a controlled atmosphere and/or in a closed enclosure, the settings linked to the extrusion and cooling temperatures described later in the description are particularly complex to master in order to ensure good repeatability of the process at an industrial level.
• the extruded cord advantageously has a width of between 5 mm and 10 mm, preferably between 6 mm and 8 mm, and very preferably 7 mm (+/- 0.5 mm). And advantageously a height comprised between 2 mm and 10 mm, preferentially between 3 mm and 5 mm, and very preferentially 4 mm (+/- 0.5 mm).
• the bead comes out of the extrusion head 51, it has a circular section, but following its placement on the receiving support 20, it flattens to ultimately have a width greater than its height, according to the data presented. above.
• Such a cord is thus relatively thin while being sufficiently mechanically strong.
• the width and/or height of the extruded bead depend in particular on the diameter of the opening of the extrusion head 51 and the distance or height at which said extrusion head is located from the surface of the receiving support 20 (for the first layer) or the last layer of extruded cords (for a multilayer structure).
• a cord having very good mechanical strength is obtained when the extrusion distance or height corresponds to the opening diameter of the extrusion head 51.
• the opening diameter of the extrusion head 51 is preferably fixed, but can be variable during the extrusion time of the object 1.
• this opening diameter is variable or different during the manufacture of the decorative object 1, the preferred ratio previously defined between the distance or height of extrusion and the opening diameter of the extrusion head, remains valid. Thus, if the opening diameter is modified during manufacturing, then the extrusion distance or height is modified accordingly.
• the extrusion head 51 is secured to a moving means.
• this displacement means is a robotic manipulation arm 30.
• the extrusion head 51 is secured to this robotic arm 30, which moves it longitudinally, transversely and optionally vertically.
• the arm 30 is a 3-axis articulated arm or, preferably, a 6-axis articulated arm.
• Such an articulated arm makes it possible to move the extrusion head 51 in translation along the axes X (abscissa), Y (ordinate) and Z (side) of a Cartesian frame, or orthonormal frame.
• the extrusion head 51 remains oriented vertically, to keep the direction of extrusion perpendicular to the surface of the receiving support 20.
• a 3-axis articulated arm makes it possible to produce relatively complex objects, in 2D or 3D, with one or more contours curves, like the one shown in Figure 1.
• the robotic arm 30 comprises: a base 32 rotatably mounted along a vertical axis on a base 35; a main arm 31 rotatably mounted along a horizontal axis on the base 32; a forearm 33 mounted so as to be able to rotate along a horizontal axis on the main arm 31.
• a joint makes it possible to assemble a coupling head 34 at the distal end of the forearm 33, which head cooperates with a member coupling 30 of the extrusion die 50.
• the dimensions of the main arm 31 and the forearm 33 are adapted to the use of the robotic arm 30, that is to say to the manufacture of the object 1 on the receiving support 20.
• Actuating means such as cylinders and/or rotary motors, arranged at these joints, produce translational and possibly rotational movements of the extrusion head 51.
• the direction and the speed of movement of the robotic arm 30 are controlled by an electronic management unit.
• This management unit is in particular in the form of a portable or fixed computer, provided in particular with a processor, microprocessor or CPU (for Central Processing Unit) and a memory, in which is recorded software whose instructions, when they are executed by the processor, microprocessor or CPU, make it possible to control the movement of the extrusion head 51 in space.
• the term "software” can be understood as: computer application, computer programs or software. For the sake of clarity, it should be understood within the meaning of the invention that "the robotic arm 30 does something” means “the software executed by the processor, microprocessor or CPU of the electronic management unit does something”.
• the robotic arm 30 is controlled so that the speed of movement of the extrusion head 51 is between 50 mm/s and 110 mm/s, this speed depending in particular on the viscosity of the extruded cord.
• a displacement speed of between 50 mm/s and 60 mm/s is preferred, this speed range making it possible to obtain a bead with a particularly aesthetic smooth appearance, in particular when its viscosity at the outlet of the extrusion head 51 is comprised between 400 and 450 Pascal per second defined according to the ISO 11443 standard.
• the electronic management unit also manages the extrusion die, that is to say in particular the supply of polymer-based composition and the extrusion rate.
• the displacement of the extrusion head 51 along a predefined trajectory makes it possible to manufacture an object 1 by adding material (additive manufacturing), and more particularly by a bead of extruded thermoplastic material which, if necessary, stacks in layers. These layers can be stacked on top of each other and/or next to each other. This stacking creates the volume of the object.
• the trajectory of the extrusion head 51 along the X and Y axes, and possibly Z, makes it possible to produce the curved contours of the object 1.
• a designer draws object 1 using a computer-aided design (CAD) tool.
• the file obtained is processed by the software stored in the memory of the management unit, which organizes the trajectory of the extrusion head 51 for the production of the object 1.
• the robotic arm 30 is controlled along this trajectory, from so that the extrusion head 51 deposits a first layer of bead on the support 20 until the final object 1 is obtained.
• Object 1 is thus obtained quickly, precisely and with optimal repeatability.
• the object 1 comprises a plurality of layers of extruded cords, each successive layer, after the first layer, then forms the support for receiving the next layer of extruded cord.
• Figure 7 illustrates an alternative embodiment where the extrusion head 51 is secured to a carriage 8 which is movable along the axes X, Y and Z of a Cartesian coordinate system.
• the carriage 8 is for example movably mounted on a first slide - or rail - 80 of axis X.
• This first slide is itself movably mounted on a second slide 81 of axis Y.
• a drive mechanism for example of the rack or jack type, driven by the control unit aforementioned management, makes it possible to translate the carriage 8 on the first slide 80, and to translate said first slide on the second slide 81. It is thus possible to move the extrusion head 51 longitudinally and transversely with respect to the surface of the support 20.
• the vertical movement of the extrusion head 51 (along the Z axis) is made possible by mounting the second slide 81 movable in translation on vertical guides 83.
• a drive mechanism for example of the rack or jack type, controlled by the aforementioned management unit, makes it possible to translate the second slide 81 along the vertical guides 83.
• a similar result is obtained by securing the extrusion head 51 to an overhead crane.
• the extrusion head 51 is fixed and it is the support 20 which is moved. It is in this case the support 20 which is secured to a means of movement of the robotic arm 30 or carriage 8 type mentioned above, the movement of said plate being controlled by the management unit.
• the extruded cord is deposited on the receiving support 20 by the effect of gravity.
• effect of gravitation refers to the fact that the movement of the extruded bead, from its exit from the extrusion head 51 to the receiving support 20, is mainly constrained or directed by the weight of said cord. This effect is made possible in particular by the fact that the extrusion head 51 is arranged or oriented vertically, in other words in the direction of application of the gravitational force.
• FIG 3 shows a first layer C of an extruded bead on the receiving support 20.
• this receiving support 20 introduces himself in the form of an L, with two rectangular portions 21, 22 of substantially identical shape and dimensions extending perpendicular to one another. These two rectangular portions 21, 22 each form the end portions of the receiving support 20 while a square portion 23 is arranged at the junction angle formed between these two end portions 21, 22.
• the rectangular end portions 21, 22 have a length of between 50 cm and 2 m and a width of between 50 cm and 150 cm.
• the junction portion 23 is a square with a length of between 50 cm and 150 cm, it being considered that the width of the end portions 21, 22 is advantageously equal to the length of the side of the junction portion 23 so as to that the end edges of the receiving support 20 are indeed continuous and essentially linear or rectilinear.
• this receiving support 20 has a thickness of between 5 mm and 30 cm. Secondary functions of this receiving support 20 consist in receiving the extruded cord without the latter adhering to the receiving support 20, nor of course being deformed or degraded by the latter.
• the receiving support 20 has a general L-shape, the robotic arm 30 being located close to the junction portion 23 substantially at equal distance from the end portions 21, 22. It is also possible to provide that the receiving support 20 is in the general shape of a square or circular frame surrounding the robotic arm 30, the latter being completely surrounded or surrounded by the receiving support 20. Finally, the receiving support 20 may have a general I-shape or even a general U-shape with three sides surrounding the robotic arm 30.
• the reception support 20 is mounted on an elevation base 40 which makes it possible to place the reception support 20 at a height from the ground of between twenty centimeters and one meter, so as to adapt to the dimensions of the robotic arm 30 and to facilitate the gripping and handling of the object 1 carried out on the support 20. Cooling of the first layer of extruded cord
• the applicant has surprisingly found that by cooling the support 20 (and not by heating it as recommended by the aforementioned documents FR3075313 and FR3069800), a first layer C is obtained having aesthetic, mechanical and optimum physico-chemical properties for the various uses, in an often very harsh environment, envisaged for the decorative object 1.
• the cooling of the support 20 makes it possible to force the cooling of the first layer C by conduction.
• the extruded bead thus drops rapidly in temperature so that the final polymerization and/or crosslinking reactions are stopped outside the extrusion die.
• the first layer C is then frozen in an unstable state.
• the criterion preferably sought in the context of the present invention is the elongation at break criterion which must be high enough to prevent the object from being brittle.
• Another criterion is the withdrawal criterion which should advantageously be at most equal to 2%.
• the cooling kinetics had an influence on the aesthetic qualities and the mechanical properties of the extruded cord.
• the best results are obtained when the cooling rate of the first layer C is between 250°C/min and 350°C/min, preferably between 290°C/min and 310°C/min and very preferably 300°C /min (+/- 5°C/min).
• the receiving support 20 is made of aluminum, or an aluminum alloy, or copper or a copper alloy, then we improve again the results in terms of shrinkage and mechanical properties.
• the support 20 then has an additional function of mechanical adhesion suitable for the extruded cord. It is also noted that the first layer C remains easily detachable, without degradation, from the reception support 20.
• the support 20 also has a coating intended to allow chemical adhesion of the extruded bead.
• This coating consists of a polymer coating, from a few microns (pm) up to one or more millimeters (at most 2 mm).
• this coating consists of a polyetherimide (PEI).
• the support 20 incorporates a cooling circuit in which circulates a cold fluid (glycol water, expanded air, ...) and which will allow said support to be cooled. This fluid will absorb the heat from the bead when it is extruded onto the support 20 and cool it.
• a cold fluid glycol water, expanded air, ...)
• Other means of cooling the support 20 suitable for those skilled in the art can be envisaged.
• the criterion preferably sought is the elongation at break criterion, which must be high enough to prevent the object from being brittle.
• Another criterion is the withdrawal criterion which should advantageously be at most equal to 2%.
• a bead C is obtained with low shrinkage and satisfactory mechanical properties. , even very satisfactory.
• the extruded cord C has good aesthetic qualities, and in particular a uniform color, a smooth and shiny appearance, etc. Remarkably good results (in terms of shrinkage, mechanical and aesthetic properties) are obtained in the range from -10°C to +10°C, but quite satisfactory results are obtained outside this range when the cooling temperature was below ambient temperature.
• the cooling kinetics had an influence on the aesthetic qualities and the mechanical properties of the extruded cord.
• the best results are obtained when the cooling rate of the bead C is between 250°C/min and 350°C/min, preferably between 290°C/min and 310°C/min and very preferably 300°C/min (+/- 5°C/min).
• the gas blown on cord C can be compressed air or nitrogen gas (dinitrogen).
• a dry gas is used, the dew point of which is less than -20° C., preferably less than or equal to -40° C. Indeed, as shown in [Table 1], humidity can have a negative influence on the properties of the bead.
• This dew point can be measured with conventional measuring devices, for example a thermo-hygrometer marketed by the company TROTEC(R)SOR the reference T260.
• the first layer can be cooled by means of the receiving support 20 and the following successive layers are then cooled by gas blowing.
• the gas is blown onto the first layer of cord extruded onto the support 20 (which may or may not be cooled) and, if necessary, onto the following successive layers.
• the steps of extruding the bead C and blowing the gas are synchronized, these two steps being carried out concomitantly during the movement of the extrusion head 51. In other words, the bead is cooled as soon as it is deposited on the support 20 and/or on another lower layer in the case of a multilayer structure.
• one or more gas blowing nozzles 9 are secured to the extrusion head 51. This ensures that the trajectory of the nozzles 9 coincides with the trajectory of the extrusion head when the latter extrudes the bead C. Depending on the width of the bead C and to accelerate its cooling, it may be advantageous to provide several nozzles arranged so that they each act simultaneously on a portion of the surface of said bead. According to one embodiment, these nozzles 9 are connected to a compressor with desiccant dryer and refrigerant 90. According to another embodiment, the cooling takes place by means of a vortex tube fixed at the level of the cooling head 51. can for example use a vortex tube with nozzles marketed by the company Meech® under the reference Coldstream®.
• the blowing nozzle or nozzles are secured to a means of movement separate from that of the extrusion head 51.
• the nozzles can for example be installed on another robotic arm which is controlled so that said nozzles move at the same time as the extrusion head 51.
• the two robotic arms can be controlled by the same management unit.
• only the extrusion head 51 is fixed on the robotic arm 30, the extrusion die 50 being offset from said arm.
• the shape and dimensions of the receiving support 20 are variable, depending on the decorative object 1 to be produced, but above all depending on the layout and dimensions of the robotic arm 30. The larger these are, the larger the dimensions of the support reception 20 can be varied and large.
• the robotic arm 30 can have as many sections as necessary or useful for the manufacture of the decorative object 1.
• the shape and the degree of freedom of the robotic arm 30 are variable insofar as they offer the possibility to bring the extrusion head 51 to the desired height of the receiving support 20, taking into account the opening diameter of the extrusion head 51.
• the first layer of extruded bead can be cooled not only by conduction with a cooled receiving support 20 but also by convection by gas blowing. Also, when the first layer of extruded cord is cooled by conduction with the cooled receiving support, the other layers can be convection cooled by gas blowing, or not be cooled.
• Means other than the nozzles 9 can be used to blow gas onto the extruded bead, for example fans or air outlets.
• the use of the verb "to comprise”, “to understand” or “to include” and of its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim.

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• 2022
  • 2022-04-22 WO PCT/FR2022/000040 patent/WO2022223889A1/fr active Application Filing
  • 2022-04-22 EP EP22727211.9A patent/EP4326528A1/de active Pending

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