FR3126332A1 - 3D printing control - Google Patents

Abstract

The present invention relates to a device for additive manufacturing (1) of material comprising an application head (3) mounted to move along 3 axes (x, y, z), said application head comprising a nozzle (30) through which the material, having a given viscosity, is extruded, with a given rate, on a manufacturing surface, the movement of the application head, at a given speed, is controlled by a control unit, characterized in that said head of application is provided with distance measuring means (4) arranged to measure the distance between the application head nozzle and the manufacturing surface and send this measurement of the distance between the nozzle and the manufacturing surface to said command to detect a compaction of the deposited material and generate a command making it possible to compensate for this compaction. Fig 1

Description

3D printing control

The present invention relates to the field of additive manufacturing based on mortar or concrete.

Prior art.

Additive manufacturing brings together the processes for manufacturing parts in volume by adding material in successive layers from a 3D model. This additive manufacturing originally uses resin as materials added in successive layers. The range of usable materials then expanded to plastics and metals, while the use also expanded to allow the manufacture of larger and larger objects.

Naturally, this additive manufacturing technique has been used for the manufacture of buildings, mortars or concrete being used as materials extruded by said nozzle.

Material such as concrete or mortar is extruded from a nozzle guided along three axes x, y, z to allow the manufacture of objects. The realization of the different layers being carried out by translation, in height / along the z axis, or rotation of the print head and therefore of the nozzle. This translation along the Z axis by a defined distance allows each increment to deposit the appropriate quantity and thickness of material.

However, it has been observed that with a material of the mortar or concrete type, there is the risk of the appearance of a squeezing phenomenon also called settling. Indeed, from a certain height, the material settles under the effect of its own mass because of the material itself.

However, if the material settles, then the distance between the nozzle through which the material is extruded and the surface on which the material must be deposited varies. Indeed, as the increment in height is fixed then the settlement increases this distance. If this increase is too great, then the material deposition for additive manufacturing is no longer optimal. Additive manufacturing loses quality because the layers have less adhesion to each other, which can lead to the collapse of the construction.

The invention seeks to solve the problem of the prior art by providing an additive manufacturing device which makes it possible to compensate for the compaction of the material previously deposited.

To this end, the present invention consists of a device for additive manufacturing of material comprising an application head mounted movable along three axes (x, y, z), said application head comprising a nozzle through which the material, having a given viscosity, is extruded, with a given flow rate, on a manufacturing surface, the movement of the application head, at a given speed, is controlled by a control unit, characterized in that said application head is provided with distance measuring means arranged to measure the distance between the application head nozzle and the manufacturing surface and to send this measurement of the distance between the nozzle and the manufacturing surface to the said control unit to detect a settlement of the deposited material and generate a command to compensate for this settling.

According to one example, the command making it possible to compensate for the settlement modifies the speed of movement.

According to one example, the control making it possible to compensate for the compaction modifies the viscosity of the mortar.

According to one example, the command making it possible to compensate for the settling modifies the rate at which the material is extruded.

In one example, the control to compensate for settlement changes the distance between the dispensing head and the build surface.

According to one example, the distance measuring means comprising at least one distance measuring sensor.

According to one example, said at least one distance measurement sensor is arranged so that its distance with the manufacturing surface is equal to the distance between the nozzle and the manufacturing surface.

According to one example, said at least one distance measurement sensor is arranged so that its distance with the manufacturing surface differs from the distance between the nozzle and the manufacturing surface.

According to one example, a distance value between the distance sensor and the nozzle is stored in the calculation unit, this distance value between the distance sensor and the nozzle allowing said calculation unit to calculate the measurement of the distance between the nozzle and the work surface from the distance measured by the sensor.

According to one example, said at least one distance measurement sensor uses infrared technology or ultrasound technology or laser technology.

According to one example, the distance measured between the nozzle and the manufacturing surface is compared with a reference value and in that the command making it possible to modify the position of the application head depends on this comparison.

According to one example, the additive manufacturing device further comprises a structure on which the application head is mounted, said structure making said application head mobile.

The invention further relates to a method for compensating additive manufacturing of material, said additive manufacturing of material being carried out by a device for additive manufacturing of material according to one of the preceding claims, said method consisting, after the deposition of each material layer, to make a distance measurement and to send this distance measurement to the calculation unit in order to extract therefrom the distance between the nozzle and the manufacturing surface, this measured distance between the nozzle and the manufacturing surface being compared with a reference value in order to generate a command compensating for this measured distance.

The invention further relates to a method for manufacturing a building element or a construction using the additive manufacturing device according to the invention with a building material.

Description of figures

Other features and advantages will emerge clearly from the description given below, by way of indication and in no way limiting, with reference to the appended drawings, in which:

- Figures 1 to 2 show an additive manufacturing device for the present invention;

- there represents an additive manufacturing device manufacturing an object;

- there depicts a cross-sectional view of a fabricator additive manufacturing device depositing a layer of an object;

- Figures 5 to 7 show an additive manufacturing device according to the present invention;

- there shows a sectional view of the various layers of material deposited;

Description of the invention

In Figures 1 and 2, an additive manufacturing device 1 is shown. This additive manufacturing device is used for additive manufacturing of material. This material is one or more construction materials in the form of a paste such as a plaster or a cementitious material of the mortar or concrete type. The additive manufacturing device can also be used with a material of the resin type. . The additive manufacturing device 1 comprises a frame or structure 2 on which an application head 3 is mounted. This application head 3 is movably mounted on the frame. It is understood that the structure 2 comprises an arm or gantries allowing the application head 3 to move along at least three axes X, Y, Z. this movement along at least three axes makes it possible to use the X and Y axes to follow the contour of the object to be manufactured, while the Z axis makes it possible to adjust the height of the application head 3 to superimpose the layers C as visible on the .

The application head 3 comprises a nozzle 30 through which the material, here the mortar, is extruded. This application head is connected to a pump and a material tank.

The additive manufacturing device 1 further comprises a control unit (not shown). This control unit is connected to the structure 2 to control the movement of the application head along three axes. The control unit is also connected to the application head 3 and to the containing pump assembly in order to control the pump so that it can send the material, such as the building material, from the reservoir to the application head. 3. Thus, the control unit manages the displacement of the structure 2 and the extrusion of material so that the material can be extruded at a precise place, with a precise quantity.

Cleverly according to the invention, the application head 3 further comprises distance measuring means 4. These distance measuring means 4 are arranged to make it possible to compensate for the settling of the material deposited by the additive manufacturing device.

For this, the distance measuring means 4 are arranged to measure the distance between the application head and the surface on which the material must be deposited, also called the manufacturing surface. The distance measuring means 4 comprise at least one distance sensor 40 as visible in FIGS. 5 and 6. This distance sensor 40 is a sensor using laser or ultrasound technology or any other technology that may be useful, such as infrared. This distance sensor 40 is connected to the control unit of the additive manufacturing device 1.

This distance sensor 40 includes or is associated, optionally, with a calculation unit allowing in particular an analog/digital conversion. In this case, the calculation unit is arranged between said distance sensor 40 and the control unit.

The data representative of the distance measured by the distance sensor 40 is sent, optionally after passing through the calculation unit, to the control unit which processes this data representative of the measured distance. The processing of this data representative of the measured distance makes it possible to generate a command.

More particularly, the processing of the data representative of the distance measured by the distance sensor 40 depends on its configuration. This means that it depends on the positioning of said distance sensor 40 on the application head 3.

The purpose of the distance measuring means 4 is, in particular, to measure the distance between the outlet of the nozzle through which the material is extruded and the surface on which said material is deposited. This distance called working distance Dw is a distance which is defined beforehand and which corresponds to the thickness E of deposited material as visible at the . Thus, in theory, after a first turn along the contour of the object to be manufactured, a thickness E of material is deposited and therefore the application head is translated along the Z axis by a distance Dw, equal to l thickness E so that the same thickness E of material can then be deposited again.

However, depending on the positioning of the distance sensor 40, the distance Dm measured by the sensor is not necessarily said distance Dw. The distance sensor 40 is positioned so that the measurement is made orthogonal to the manufacturing surface.

Indeed, on the , we can see a first position configuration of the distance sensor. This configuration is ideal in that the distance Dm measured by said distance sensor 40 is equal to the distance between the outlet of the nozzle 30 and the surface on which the material is deposited.

However, on the , a configuration is shown in which the distance Dm measured by said distance sensor 40 is not equal to the distance between the outlet of the nozzle 30 and the surface on which the material is deposited. Indeed, the distance sensor 40 is positioned "recessed" so that the measured distance Dm is equal to the distance between the outlet of the nozzle and the surface on which the material is deposited added to the distance Dc between the sensor of distance 40 and nozzle outlet 30.

This configuration of the then requires a calculation step in which the distance Dm measured by the distance sensor 40 is reduced by the value of the distance between the distance sensor and the outlet of the nozzle. This value being fixed, it is previously calculated and stored in the control unit.

The distance Dm measured by the distance sensor 40 is then compared with the value of the desired working distance Dw. This comparison makes it possible to determine the presence of settlement.

If the value measured by the distance sensor 40 is equal to the desired working distance Dw then the control unit considers that there is no settling and no corrective measure is taken.

If the value measured by the distance sensor 40 is different from the desired working distance Dw then the control unit considers that there is compaction and a corrective measure is initiated. This corrective measure consists in calculating the settlement by subtracting the value measured by the distance sensor 40 with the desired value Dw. As settlement tends to increase the distance between the nozzle and the surface then the measured value should be greater than the desired Dw value. From this subtraction, there results a settlement value Dt as visible at the . This shows in A, the deposit of 3 layers, theoretical, with a thickness without settling. In B, we can see the deposition of 3 layers with a Dt settlement. This Dt settlement value is used to generate a correction command to the structure supporting the application head.

In a first embodiment, the correction command consists of a translation command of the application head along the Z axis. This translation of the application head along the Z axis is such that it allows said head to application of moves a distance Dt towards the build surface. We then understand that the application head descends. Indeed, as compaction means that the manufacturing surface is lower than expected, then the application head must be lowered to compensate.

Once the position of the application head 3 relative to the manufacturing surface has been corrected, the deposition of material can be carried out, that is to say that the material with be deposited while the application head moves along the outline of the object to be crafted. Once the material has been deposited along this contour, a new translation along the Z axis of the Dw value is carried out and a new distance measurement is made in order to determine any settlement.

According to a second embodiment, the correction control signal operates on parameters other than the position along the Z axis. Indeed, the deposition of the material by the application head depends on several parameters such as the speed of movement of the application head 3, the viscosity of the material to be deposited and of the rate at which said material is extruded. Thus, the deposition of the material by the application head 3 is carried out with a given speed, a given flow rate and a given viscosity.

In this second execution, the control signal is such that it allows the control unit to act on the speed of movement of the application head, and/or on the viscosity of the material to be deposited and/or on the material flow. The action on one or more of these parameters thus makes it possible to compensate for the settlement.

For example, in the case of speed, the control unit will act to increase this speed. At a constant flow rate, an increase in speed results in less deposited material and therefore less weight. As the weight partly determines the settlement, a decrease in weight leads to a decrease in settlement. The reasoning for throughput is similar. By playing on the flow rate, we can modify the quantity of material

Concerning the viscosity, the settlement compensation is done by increasing the viscosity. Indeed, by being more viscous, the material sags less. This viscosity adjustment can be made by adding a chemical agent which increases this viscosity.

Thus, the distance sensor according to the invention advantageously makes it possible to correct any settling so as to obtain optimal additive manufacturing.

In a first variant, the distance measuring means comprise two distance sensors 40 as visible at the . These distance sensor sensors make it possible to have two distance measurements Dm1, Dm2 and thus to increase the reliability of the measurement in the event of a problem on a sensor. These two sensors can be positioned so that the distances between said sensor and the manufacturing surface of each are identical. But it is possible to position them so that the distances between said sensor and the manufacturing surface of each are different.

In a second variant, the distance measuring means 4 are used in order, moreover, to make it possible to check whether the settling is constant. Indeed, it is possible that, depending on the contour of the part to be manufactured, the settlement may be variable along said contour of the part to be manufactured. Thus, the measurement of the distance can be done at different points of the contour, the application head moving between each measurement, or over the entirety of said contour. In the latter case, the distance measurement is carried out continuously during the displacement of the application head n with an appropriate measurement frequency.

Given that the contour of the part to be manufactured consists of a series of coordinates (x, y), it is possible to link the distance measurements operated by said distance sensor 40 in order to the coordinates. This then allows the control unit to generate a correction command that binds, for said coordinates, a translation along the appropriate z axis.

Thus, after the step of depositing the material along the contour, the application head is again moved along said contour to take the distance measurements.

In another variant, the distance sensor 40 is used for the prior positioning of the application head. Indeed, the first layer of material is deposited on the ground or the base surface on which said object is manufactured. This base surface being stable, compaction is not possible but the use of the distance sensor 40 can be useful for the calibration of the additive manufacturing device 1. This calibration makes it possible to compare the distance between the outlet of the nozzle and the base surface after the positioning of the application head by the structure and the control unit and the distance measured by the distance sensor.

Of course, the present invention is not limited to the example illustrated but is susceptible to various variants and modifications which will become apparent to those skilled in the art.

Claims (14)

Device for additive manufacturing (1) of material comprising an application head (3) mounted movable along 3 axes (x, y, z), said application head comprising a nozzle (30) through which the material, having a viscosity given, is extruded, with a given rate, on a manufacturing surface, the movement of the application head, at a given speed, is controlled by a control unit, characterized in that said application head is provided with distance measuring means (4) arranged to measure the distance between the application head nozzle and the work surface and send this measurement of the distance between the nozzle and the work surface to said control unit to detect settling material deposited and generate a command to compensate for this compaction. Device according to the preceding claim, in which the control making it possible to compensate for the settling modifies the speed of movement. Device according to one of the preceding claims, in which the control making it possible to compensate for the compaction modifies the viscosity of the mortar. Device according to one of the preceding claims, in which the control making it possible to compensate for the settling modifies the rate at which the material is extruded. Device according to one of the preceding claims, in which the control making it possible to compensate for the settling modifies the distance between the application head and the manufacturing surface. Device according to one of the preceding claims, in which the distance-measuring means comprise at least one distance-measuring sensor (40). Device according to the preceding claim, in which the said at least one distance measuring sensor is arranged so that its distance with the manufacturing surface is equal to the distance between the nozzle and the manufacturing surface. Apparatus according to claim 6, wherein said at least one distance measuring sensor is arranged so that its distance from the work surface differs from the distance between the nozzle and the work surface. Device according to Claim 8, in which a value of the distance between the distance sensor and the nozzle is stored in the calculation unit, this value of the distance between the distance sensor and the nozzle allowing the said calculation unit to calculate the measurement of the distance between the nozzle and the work surface from the distance measured by the sensor. Device according to one of Claims 6 to 9, in which the said at least one distance measuring sensor uses infrared technology or ultrasound technology or laser technology. Device according to one of the preceding claims, in which the distance measured between the nozzle and the manufacturing surface is compared with a reference value and in that the command making it possible to modify the position of the application head depends on this comparison . Device according to one of the preceding claims, in which it further comprises a structure (2) on which the application head (3) is mounted, said structure (2) making said application head mobile. Process for compensating additive manufacturing of material, said additive manufacturing of material being carried out by a device for additive manufacturing of material according to one of the preceding claims, said process consisting, after the deposition of each layer of material, in making a distance measurement and in sending this distance measurement to the calculation unit in order to extract therefrom the distance between the nozzle and the manufacturing surface, this measured distance between the nozzle and the manufacturing surface being compared with a reference value to generate a command compensating for this measured distance. Method for manufacturing a construction element or a construction using the additive manufacturing device according to one of Claims 1 to 12 with a construction material.