SYSTEM AND METHOD FOR PRODUCING A BUILDING MATERIAL

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a system and method for manufacturing a printed work.

[0002] More specifically, the invention relates to a system and method for manufacturing a building material comprising a printed matrix and a reinforcing fiber. STATE OF THE ART

[0003] 3D construction printers are known which enable the construction of buildings or parts of buildings by depositing material in successive layers on a deposition plane, from a three-dimensional model of the structure.

[0004] The resulting structure, however, has poor mechanical properties. In fact, progressive stiffening, or setting, of the layers is necessary to ensure the dimensional stability of the structure. However, the faster drying at the interlayer, and delayed drying in the center of the layer, makes the bonds between the layers mechanically weak.

[0005] Solutions are known for reinforcing a printed building material, consisting of placing reinforcing elements, such as steel bars, nails, or screws, in the interlayer. Alternatively, the building material can be printed around a mesh. However, these solutions remain relatively limited because they are not compatible with all shapes and / or compositions of the printed material. Local decohesion is also observed in these types of reinforcements due to the lack of adhesion between the reinforcing element and the printed material. In addition, they are complex, non-automatable, and expensive.

[0006] One solution to these problems is to add reinforcing fibers to the printed building material. For example, pieces of fiber can be introduced directly into the building material before printing. However, this solution is unsatisfactory when it comes to improving adhesion between layers and makes extrusion difficult.

[0007] DE 10 2017 221661 A1 discloses a system and method for manufacturing a composite building material according to the preamble of respective claims 1 and 6.

[0008] An objective of the present invention is to provide a manufacturing system and method for overcoming the drawbacks of the prior art, and for obtaining construction materials with improved mechanical performance. SUMMARY

[0009] The invention therefore relates to a system for manufacturing a composite construction material comprising a printed matrix and a continuous fiber embedded in said matrix, the system comprising a print head configured to deposit the matrix by depositing material in successive layers on a deposition plane, and an injection device configured to introduce the continuous fiber into the matrix deposited by the print head.

[0010] The injection device includes: a dispensing head configured to deliver the fiber, said dispensing head being movable in a vertical direction perpendicular to the deposition plane, between a high position and a low position; a drive device configured to oscillate the dispensing head between the high position and the low position; and an elastic return element configured to passively return the dispensing head from the low position to the high position.

[0011] Advantageously, the system allows the fiber to be introduced into the printed matrix during deposition and thus to create a continuous pattern in said matrix. The construction material obtained does not require the successive introduction of reinforcing elements.

[0012] In the present invention, by "reinforcement" we mean the material produced and introduced, thanks to the injection device, into a printed matrix. By "printed matrix" means a material printed with a 3D printer. The printed matrix can be a composite material, for example concrete, or any other colloidal matrix material.

[0013] Specifically, moving the dispensing head along the vertical direction allows the fiber to be introduced in a pattern through multiple layers, thereby increasing the adhesion between the printed matrix layers.

[0014] Advantageously, the passive return of the dispensing head from the low position to the high position makes it possible to simplify the operation of the drive device. Indeed, in this exemplary embodiment, the movement of the dispensing head from its low position to its high position can be ensured by the elastic return element, while the movement in the opposite direction (from the high position to the low position) can be ensured by the drive device.

[0015] By reducing the torque supplied by the drive device, it is possible to use a drive device with more compact dimensions.

[0016] In one embodiment, the injection device comprises a first feed device configured to bring the fiber to the distribution head. A continuous tubular guide (PTFE tube for example) can advantageously be used.

[0017] The first feeding device may, for example, comprise a spool. Advantageously, a spool makes it possible to store a very long and continuous fiber.

[0018] In one embodiment, the dispensing head comprises a hollow needle capable of being traversed by the continuous fiber.

[0019] A hollow needle can deliver and guide a semi-rigid or flexible fiber as well as a fluid material.

[0020] In one embodiment, the dispensing head is configured to deliver an interphase material with the fiber.

[0021] This configuration allows for the delivery of an interphase material. The interphase material may be a material that impregnates the fiber, or a material that envelops the fiber, or one that is deposited together with the fiber in the printed matrix. Advantageously, the interphase material forms an interface between the fiber and the printed matrix. It therefore allows, among other things, to improve the adhesion between the fiber and the printed matrix.

[0022] In one embodiment, the injection device comprises a second feeder device configured to deliver the interphase material to the dispensing head.

[0023] As mentioned above, in one embodiment, the dispensing head comprises a hollow needle.

[0024] Advantageously, the needle has a diameter between 2 mm and 3 cm, and a length between 50 mm and 200 mm. A needle of this dimension can easily be introduced into a printed matrix during deposition, and pass through at least one deposited layer. In addition, it allows, thanks to its hollow part, to obtain a sufficient flow rate of interphase material.

[0025] In one embodiment, the system includes a controllable flow rate pump for delivering the interphase material to the dispensing head.

[0026] Advantageously, the pump can deliver a liquid interphase material.

[0027] In one embodiment, the drive device is configured to oscillate the dispensing head between the high position and the low position at a predetermined frequency and amplitude.

[0028] This configuration allows the dispensing head to be periodically introduced into the printed matrix at a predetermined frequency. At each introduction, at least one interlayer is crossed by the dispensing head. The number of interlayers crossed depends on the amplitude of the oscillation.

[0029] The fiber delivered by the oscillating dispensing head thus forms a periodic and continuous pattern in the printed matrix. The pattern has an amplitude determined by the amplitude of the oscillation, and a periodicity determined by the oscillation frequency.

[0030] The invention also relates to a method of manufacturing a composite construction material comprising a printed matrix and a continuous fiber embedded in said matrix, the method comprising a step of depositing at least two layers of printed matrix, and a step of inserting the continuous fiber inside the at least two layers.

[0031] Advantageously, the continuous fiber ensures multidirectional continuity of the reinforcement. In addition, the continuous fiber pattern crosses, going back and forth, at least two inter-layers, which improves the adhesion between the printed matrix layers.

[0032] Overall, the process produces a composite material with improved mechanical strength, thanks to the improved adhesion between the deposited layers and the multidirectional continuity of the reinforcement. Furthermore, the process is very fast because the reinforcing fiber is delivered into the printed matrix during printing. Therefore, no subsequent step of introducing a reinforcing material is required.

[0033] In one embodiment, the printed matrix comprises concrete, concrete foam, insulating foam, a clay material. These building materials are compatible with additive manufacturing based on printing by extrusion / deposition of material in successive layers.

[0034] In one embodiment, the method further comprises, during the insertion step, introducing an interphase material with the continuous fiber through the at least two layers.

[0035] Advantageously, the interphase material makes it possible to improve the adhesion between the fiber and the printed matrix.

[0036] In one embodiment, the printed matrix comprises concrete, concrete foam, insulating foam, a clay material.

[0037] For example, the interphase material can be a cementitious matrix, an earth-based matrix, a polymer matrix. These materials are characterized by high mechanical performance and high adhesion to the fiber.

[0038] In one embodiment, the fiber is a steel fiber, a carbon fiber, a plant fiber, or a synthetic fiber, preferably in the form of a braid, a wire, or a strand.

[0039] Advantageously, a fiber in the form of a porous braid (or strand) makes it possible to improve adhesion with the matrix and / or the interphase material.

[0040] In one embodiment, the distance between the high position and the low position is adjustable between 5 cm and 50 cm in accordance with the dimensions of the printed structure.

[0041] In one embodiment, the speed of movement of the dispensing head between the high position and the low position (oscillation frequency) is adjustable in order to vary the periodicity of the fiber pattern. By varying the periodicity of the fiber pattern it is possible to vary the density of reinforcements.

[0042] Preferably, the periodicity of the fiber pattern is between 5 cm and 20 cm.

[0043] According to the invention, the method uses a system as described above. In this case, the deposition step comprises the deposition of at least two layers of matrix printed by the print head, and the insertion step comprises the following successive phases: an injection phase during which the dispensing head is moved along the vertical position from its high position to its low position; a return phase during which the dispensing head is moved along the vertical position from its low position to its high position; a neutral phase during which the dispensing head is in the high position.

[0044] The fiber is delivered through the distribution head during these three phases, resulting in a continuous fiber embedded in the printed matrix.

[0045] In one embodiment, an interphase material is introduced through printed matrix layers via the dispensing head at least during the injection phase.

[0046] The delivery of the interphase material may be prolonged with a lower flow rate to promote interlayer adhesion. Using this interphase material in this way may, where appropriate, help to resolve the drying problems mentioned above. DETAILED DESCRIPTION

[0047] There Figure 1 shows a system 1 comprising a print head 11 for depositing material (the printed matrix) in successive layers 111, and an injection device 12 for delivering a fiber 122.

[0048] The injection device 12 comprises a fixed part, integral with the print head 11 and a distribution head 121.

[0049] By "dispensing head" is meant the movable part of the injection device 12. The dispensing head 121 is capable of receiving a product (a fiber, a fluid, etc.) stored in a supply device 123 such as a container, a reel, a reservoir, and conveying this product from its supply device 123 to the printed matrix.

[0050] For example, the dispensing head 121 may comprise one or more channels communicating, on the one hand, with the feed device 123 containing the product to be dispensed and, on the other hand, with the exterior. In this case, during its movement, the dispensing head 121 may take a position in which the end communicating with the exterior is in contact with the printed matrix, thus allowing the introduction of the product into the matrix.

[0051] The system 1 thus makes it possible to obtain a composite construction material comprising a printed matrix, i.e. the material deposited by the print head 11, and a fiber 122 embedded in this printed matrix.

[0052] The print head 11 moves on a horizontal xy plane (direction indicated by the white arrow), also called the "deposition plane". During its movement, the print head 11 deposits the printed matrix layers 111 on the xy deposition plane.

[0053] The injection device 12 is integral with the print head 11. Its movement on the xy deposition plane is therefore synchronized with that of the print head 11.

[0054] Accordingly, if the print head 11 is capable of rotation around a vertical axis z, the injection device 12 can also follow this rotation.

[0055] The injection device 12 secured to the print head 11 makes it possible to use a single command (for example a G-code) for the injection device 12 and for the print head 11.

[0056] For example, the injection device 12 may be attached to the print head 11 or secured to the print head 11 via a clamp or other reversible securing mechanism. The reversible securing to the print head 11 provides a versatile injection device that can be adapted to any print head.

[0057] The injection device 12 comprises a dispensing head 121 which is intended to deliver the fiber 122 within the matrix printed by the print head 11. For example, the fiber 122 can be guided along the dispensing head 121 by means of a guide 127. A PTFE-based tube can advantageously be used to guide the fiber along the injection device. Alternatively, the dispensing head 121 can have a lumen for guiding the fiber.

[0058] Advantageously, the guide 127 may be made of a material that limits friction, for example Teflon. The guide 127 may be, for example, a ring or a tube.

[0059] Preferably, the guide 127 is a hollow needle. A needle has a shape particularly suited to piercing the printed matrix and passing through its layers.

[0060] The hollow needle allows for greater versatility as it allows the fiber to be delivered along an outer surface of the needle or inside the hollow portion of the needle. In addition, a hollow needle also allows for the injection of a fluid material within the printed matrix.

[0061] The movement of the dispensing head 121 along the vertical direction z is ensured by a drive device 124, which causes the dispensing head 121 to oscillate between a low position and a high position.

[0062] The injection device 12 also comprises an elastic return element 125. In this case, the drive device 124 can ensure the movement of the dispensing head 121 from the high position to the low position and the passive elastic return element 125 can return the dispensing head from the low position to the high position. The use of an elastic return element 125 is advantageous because it makes it possible to increase the responsiveness of the system 1. Indeed, increasing the responsiveness of the system 1 makes it possible to minimize the damage in the printed matrix due to the penetration of the injection device 12 advancing with the print head 11 (the higher the printing speed, the shorter the oscillation of the injection device 12 must be, otherwise a significant portion of the printed matrix would be damaged).The elastic return element 125 being passive, it allows instantaneous reactivity unlike the reactivity time of an active actuator (such as a motor). Indeed, the return element 125 moves the dispensing head from the low position to the high position instantly as soon as the force applied to the elastic return element 125 is cancelled. This elastic return element therefore makes it possible to overcome the reactivity requirements of a possible motor and the associated cost: such a motor would rotate a rocker arm at a known speed and therefore a known period of time, and the return would take place when the head of the oscillating needle is not in contact with a rocker arm.

[0063] In the example embodiment illustrated in Figure 1, the passive elastic return element 125 is a helical spring wound around an upper end of the dispensing head 121. This spring bears on the body of the injection device 12, which constrains it when the dispensing head 121 moves from its high position to its low position. The stretching of the spring causes the translation of the dispensing head in the opposite direction, i.e. from its low position to its high position.

[0064] Advantageously, the elastic return element 125 makes it possible to simplify the operation of the drive device 124. For example, the drive device 124 may be a stepper motor or a servomotor. In this case, the movement of the dispensing head from the low position to the high position is done with the motor in freewheel mode.

[0065] Alternatively, the drive device 124 may comprise a servomotor working in both directions, a linear actuator such as a linear motor, or a cylinder capable of imparting a back-and-forth movement to the dispensing head. In this case, the injection device 12 does not comprise an elastic return element 125.

[0066] As detailed in the Figure 1 , the injection device 12 may comprise a feeder device 123 configured to feed the fiber to the distribution head. In this example, the feeder device 123 is a spool, which makes it possible to store a very long and continuous fiber.

[0067] Advantageously, the dispensing head 121 may be configured to deliver an interphase material 128 with the fiber 122.

[0068] For example, the injection device 12 may comprise a second feed device intended to contain the interphase material 128. The interphase material 128 may thus be conveyed from the second feed device to the distribution head 121 using a pump (for example a peristaltic pump) with a controllable flow rate and a pipe 126. The use of a pump with a controllable flow rate is advantageous because it makes it possible to pump an interphase material 128 characterized by high mechanical performance. The high mechanical performance makes it possible to increase the adhesion between the interphase material 128 and the printed matrix, thus making it possible to increase the charge transfer between the two materials. In addition, controlling the quantity of interphase material 128 injected into the printed matrix makes it possible to significantly increase the adhesion between the layers of the printed matrix and thus reduce the areas of mechanical weakness between these layers.Finally, the flow control by the pump makes it possible to compensate for the damage to the matrix induced by the oscillation of the injection device 12 at the heart of the matrix by an injection of material with superior mechanical performance.

[0069] In this case, an actuator can actuate the pump when the dispensing head 121 is in its low position, and stop the pump when the dispensing head 121 is in its high position. This configuration makes it possible to deliver the interphase material 128 when the dispensing head 121 is within the printed matrix. The actuator can actuate the pump as soon as the dispensing head 121 reaches the printed matrix when it moves from its high position to its low position, which makes it possible to obtain a sufficient volume of interphase material 128 even in the event of a low flow rate.

[0070] The dispensing head 121 may comprise an inlet orifice, an outlet orifice and a cavity into which said orifices open. In this case, the interphase material 128 may be introduced into the cavity of the dispensing head 121 by means of a pipe 126. This configuration makes it possible to deliver a fluid interphase material 128. The interphase material 128 thus passes through the cavity of the dispensing head 121 to the outlet orifice. Near the outlet, the fiber 122 comes into contact with the interphase material 128, which envelops it (for example if the interphase material 128 is very viscous) and / or impregnates it at least partially (liquid interphase material 128).

[0071] In an alternative embodiment (not shown), the fiber 122 is also introduced into an orifice of the dispensing head. For example, it may be introduced into the same orifice that receives the interphase material 128, or into a separate orifice.

[0072] Advantageously, the interphase material 128 forms an interface between the fiber 122 and the printed matrix which makes it possible to improve the fiber / matrix adhesion.

[0073] There Figure 2 shows a front view of the system of the Figure 1 , in which a part of the printed matrix is ​​hidden, for a better understanding of the movement of the distribution head 121, and the introduction of the fiber 122 within the printed matrix.

[0074] The trajectory of the dispensing head 121 is the result of two movements: the oscillation of the dispensing head 121 along the vertical direction z (between the high position and the low position), and its movement on the deposition plane xy.

[0075] When the dispensing head 121 is in its high position, it does not come into contact with the printed matrix.

[0076] When the dispensing head 121 is in its lower position, it is located within the printed matrix ( Figure 2 ).

[0077] The fiber 122 is delivered via the movable dispensing head 121, it therefore forms a continuous pattern in the printed matrix which follows the trajectory of the dispensing head 121. This continuous pattern ensures the multidirectional continuity of the reinforcement within the printed matrix.

[0078] Furthermore, during its oscillation along the vertical direction z, the dispensing head 121 crosses, by making several back and forth movements, at least one inter-layer 112, that is to say at least two layers 111.

[0079] As a result, the continuous pattern formed by the fiber 122 connects the layers 111 together, thus improving the adhesion between successive layers 111.

[0080] It should be noted that existing solutions for reinforcing printed construction materials do not provide satisfactory results because they do not affect the adhesion between the layers 111.

[0081] Poor adhesion between the deposited 111 layers generates heterogeneity in the mechanical performance of the printed material along the z direction perpendicular to the xy deposition plane.

[0082] Furthermore, poor adhesion between the layers 111 tends to decrease the performance of the material in bending.

[0083] There Figure 3 illustrates an example of a continuous pattern formed by the fiber 122 within the printed matrix. In this example, the fiber 122 passes through three layers 111 of this matrix.

[0084] The continuous pattern of fiber 122 is characterized by an amplitude A and a periodicity T.

[0085] Advantageously, it is possible to vary the amplitude A and the periodicity T of the pattern, by varying the amplitude and the frequency of the oscillation imposed by the drive device 124, respectively.

[0086] By varying the amplitude A of the pattern, it is possible to modify the number of layers 111 crossed by the fiber 122.

[0087] Preferably, the amplitude A of the pattern is between 5 cm and 50 cm.

[0088] By varying the frequency of the oscillation, it is possible to modify the periodicity T of the pattern. For example, the drive device 124 may comprise a motor and a controller configured to control the rotational speed of the motor. Alternatively, the drive device 124 may comprise a linear actuator such as a linear motor, or a cylinder capable of imparting a reciprocating movement to the dispensing head.

[0089] Preferably, the periodicity T of the pattern is between 5 cm and 20 cm.

[0090] The system 1 according to the invention is particularly suitable for the manufacture of a construction material. Indeed, these materials generally have the disadvantage of low tensile strength.

[0091] The printed matrix can be any printable construction material (insulating or structural). It can be a composite material, or a homogeneous material.

[0092] For example, the printed matrix can be a polymer-based matrix.

[0093] Alternatively, the printed matrix may be a cementitious matrix, such as mortar, concrete, concrete foam.

[0094] Advantageously, the cement contained in these printable cement matrices can be totally or partially replaced by an earth-based material (clay, sediment), waste from the recycling sector (and industrial co-products) or construction waste. Since cement manufacturing is a major source of CO2 emissions, replacing it with these alternative binders makes it possible to obtain a less polluting manufacturing process and to recover industrial waste.

[0095] The fiber 122 may be a synthetic fiber, for example based on metals (preferably steel), nylon, carbon, glass, aramids, polyethylene (preferably very high molar mass polyethylene).

[0096] These 122 fibers have good mechanical properties and are flexible.

[0097] Alternatively, fiber 122 can be a plant fiber, based on hemp, linen, cotton, algae.

[0098] Preferably, the fiber 122 is in the form of a braid, a wire, or a strand.

[0099] Advantageously, a fiber 122 in the form of a braid, or a strand is porous, which makes it possible to promote adhesion between the fiber 122 and the printed matrix and / or the interphase material 128. In addition, the braiding or stranding of the fiber 122 makes it possible to improve its mechanical strength.

[0100] The interphase material 128 may be a cement slurry, an earth-based matrix (e.g., sediments and / or clay), or a polymer matrix. These materials are characterized by high mechanical performance and high adhesion to the fiber 122 and the printed matrix.

[0101] The invention also relates to a method of manufacturing a composite construction material comprising a printed matrix and a continuous fiber 122 embedded in this printed matrix.

[0102] More specifically, the method comprises a step of depositing at least two layers 111 of printed matrix on an xy deposition plane, and a step of inserting the continuous fiber 122 inside the at least two layers 111.

[0103] Advantageously, the method may also comprise the introduction of an interphase material 128. In this case, the interphase material 128 is introduced with the continuous fiber 122 through the at least two layers 111, during the insertion step.

[0104] According to the invention, the method uses a system 1 comprising a print head 11 and an injection device 12 as described above. In this case, the operating mode of the system 1 according to the preferred mode is as follows.

[0105] During a deposition step, at least two matrix layers 111 are printed by the print head 11 on the xy deposition plane.

[0106] This deposition step includes an injection phase (Pi), a return phase (Pr), and a neutral phase (Pn).

[0107] During the injection phase Pi the distribution head 121 is moved along the vertical position z from its high position to its low position ( Figure 2 ). This movement is ensured by the drive device 124.

[0108] This Pi injection phase allows the 122 fiber to be introduced into the printed matrix.

[0109] During the return phase Pr the dispensing head 121 is moved along the vertical position z from its low position to its high position. According to the invention, this movement Pr is ensured by an elastic return element.

[0110] During the neutral phase Pn the distribution head 121 is in the high position. During this phase Pn there is no relative movement between the distribution head 121 and the injection device 12. Consequently, this neutral phase Pn corresponds to a horizontal line in the pattern defined by the fiber 122 ( Figure 3 ).

[0111] It should be noted that in the detailed example on the Figure 3 , an interphase material 128 is delivered during the injection phase Pi and the return phase Pr. However, the interphase material 128 can also be delivered during the neutral phase Pn, thus making it possible to advantageously resolve any drying problems.

[0112] More specifically, in this example, the print head 11 has printed five layers 111 of matrix in five successive deposition steps, and a sixth deposition step is in progress. The dispensing head 121 has delivered the fiber 122 during the fourth deposition step (i.e., after deposition of the third layer 111 of printed matrix and during the deposition of the fourth layer 111) and during the sixth deposition step (after deposition of the fifth layer 111 and during the deposition of the sixth layer 111).

[0113] To facilitate the intelligibility of the figure, the injection Pi, return Pr and neutral Pn phases are indicated relative to the fourth deposition step. BRIEF DESCRIPTION OF THE FIGURES

[0114] Figure 1 is a perspective view of a system 1 according to one embodiment of the invention. Figure 2 is a frontal view showing system 1 of the Figure 1 . Figure 3is a perspective view showing an example of a fiber-defined pattern within the printed matrix.

[0115] For the purpose of illustration, the system 1 is shown in preferred embodiments. It is to be understood, however, that the present application is not limited to the precise arrangements, structures, features, embodiments and appearances shown. The drawings are not drawn to scale and are not intended to limit the scope of the claims to the embodiments shown therein.

Claims

1. A system (1) for manufacturing a composite construction material comprising a printed matrix and a continuous fiber (122) embedded in said matrix, the system (1) comprising a print head (11) configured to deposit the matrix by successive layer-by-layer (111) material deposition on a deposition plane, and an injection device (12) configured to introduce the continuous fiber (122) into the matrix deposited by the print head (11), the injection device (12) comprising: - a distribution head (121) configured to deliver the fiber (122), said distribution head being movable along a vertical direction (z) perpendicular to the deposition plane, between a high position and a low position; - a drive device (124) configured to oscillate the distribution head between the high position and the low position; and - an elastic return element (125) configured to passively return the distribution head (121) from the low position to the high position.

2. The system (1) according to claim 1, wherein the distribution head (121) comprises a hollow needle suitable for being traversed by the continuous fiber (122).

3. The system (1) according to any one of claims 1 to 2, wherein the distribution head is configured to deliver an interphase material (128) with the fiber (122).

4. The system (1) according to claim 3, comprising a controllable flow rate pump for delivering the interphase material (128) to the distribution head (121).

5. The system (1) according to any one of claims 1 to 4, wherein the drive device (124) is configured to oscillate the distribution head (121) between the high position and the low position at a predetermined frequency and amplitude.

6. A method for manufacturing a composite construction material comprising a printed matrix and a continuous fiber (122) embedded in said matrix, the method comprising a step of depositing at least two layers (111) of printed matrix, and a step of inserting the continuous fiber (122) within the at least two layers (111), said steps being performed using the system (1) for manufacturing a composite construction material according to any one of claims 1 to 5.

7. The method according to claim 6, further comprising, during the insertion step, the introduction of an interphase material (128) with the continuous fiber (122) through the at least two layers (111).

8. The method (1) according to claim 6 or claim 7, wherein the printed matrix comprises concrete, foamed concrete, insulating foam, or a clay-based material.

9. The method (1) according to any one of claims 6 to 8, wherein the fiber (122) is a steel fiber, a carbon fiber, a plant-based fiber, or a synthetic fiber, preferably in the form of a braid, a wire, or a strand.