Patent Application
20240367344
The disclosure relates to a method and a system for producing a three-dimensional object from a curable binder composition, especially a curable mineral binder composition, with an additive manufacturing process.
In the construction industry, curable binder compositions, such as for example mineral binder compositions, are widely used for various applications. Examples of such compositions are mortar, concrete, grout, or screed compositions.
Attempts have been made for some time to produce geometrically demanding construction elements using additive manufacturing processes. The term “additive manufacturing process” or “additive production” refers to processes in which a spatial object or a molded body is produced by the targeted spatial deposition, application and/or solidification of material.
The deposition, application and/or consolidation of the material, for example the curable binder composition, is carried out in particular on the basis of a data model of the object to be generated and in particular layer-by-layer. Thus, in the additive manufacturing process, each object is typically produced from one or more layers. Usually, a formless material (for example liquids, powders, granulates, etc.) and/or a form-neutral material (for example tapes, wires) is used to manufacture an object, which is subjected in particular to chemical and/or physical processes (for example melting, polymerizing, sintering, curing). Additive manufacturing processes are also referred to as “generative manufacturing processes” or “3D printing”, among others. Additive manufacturing in the construction sector is quickly developing and projects involving this technology are becoming more and more ambitious. However, additive manufacturing is based on a rather difficult interplay between the material to be applied, for example a curable binder composition, and the application device, for example a 3D printing device. However, the physical and chemical properties of curable binder compositions, such as for example concrete mixtures, make the generative production of concrete elements very difficult. In a typical 3D concrete printing process, a dry mortar is first mixed with water and admixtures, typically containing polymers and additives, such as plasticizers, using a continuous mixing device to provide a homogeneously mixed mortar composition having a constant quality and properties. The mortar composition is pumped through a supply line having a length of several meters to a printing head and applied layer-by-layer to form a three-dimensional object. In a two-component 3D printing, the process comprises a further step of mixing the mortar composition with one or more additives, especially an accelerator, in the printing head.
Typically, high performance mortars containing low amount of water are used as the curable binder compositions in 3D printing of cementitious structures. Due to the low amount of water in the mortar, obtaining a homogeneously mixed mixture typically requires that the mixing is conducted as a high intensity mixing process, where the motor of the continuous mixing device can reach speeds of up to 2000 rpm. Due to the high intensity of the mixing step and the friction, especially between solid particles of the mortar and moving parts of the continuous mixer, a lot of heat energy is generated inside the mixer. It has been found out that the temperature of the mortar composition can increase as much as by 10° C. during a mixing process, even if the lead time of the continuous mixer was in the range of seconds rather than minutes. Moreover, the pumping of the mixed mortar composition could lead to another temperature increase, which may be, depending on the type of the pump and length and dimensions of the supply line, even more significant than the temperature increase during the mixing step. Finally, in a two-component printing process, the temperature of the mortar composition will significantly increase in the printing head due to the frictional heat generated in the mixing step and also due to exothermic chemical reactions resulting from mixing of the mortar composition with the hardening curing accelerators.
If the temperature is allowed to freely fluctuate during the additive manufacturing process, the mortar composition could reach temperatures that have significant adverse effects on the quality of the 3D printed object. For example, high temperature of the mortar composition alters the type and/or speed of chemical reactions of cement resulting in products having inferior mechanical properties or even blocking of the printing head. Furthermore, at higher temperatures more water is evaporated after the mortar composition has been extruded from the printing head that can result in weaker bonding between the applied layers. High temperatures of the mortar composition also make it more difficult to control the mixing and pumping steps occurring upstream of the printing head. Furthermore, the viscosity and reactivity of the mortar composition, and efficiency of the plasticizer are highly dependent on the temperature of the mortar composition. It would thus be highly desirable to be able to control the temperature of the mortar composition before it reaches the printing head and/or in the printing head.
WO 2020/260375 A1 (Saint-Gobain Weber) describes a method suitable for 3D printing of elements comprising hydraulic binder and aggregates. Thereby, a dry mortar composition comprising hydraulic binder and aggregates is mixed with water to form a wet mortar, and the wet mortar is then pumped and conveyed towards an outlet. During the conveying, at least two physical properties of the wet mortar are measured online with a sensor, whereby said physical properties include viscosity and at least one of flow rate and density. Furthermore, temperature of the wet mortar can be simultaneously measured with density, flow rate, and viscosity using the same sensor. The system for implementing the disclosed method comprises a mixing device adapted to mix a dry mortar composition comprising hydraulic binders and aggregates with water, an outlet, a pumping device adapted to pump and convey the wet mortar towards the outlet, and at least one sensor adapted to measure on-line at least two physical properties of the wet mortar. The system comprises a controller configured to adjust the mixing ratio between the water and the dry mortar depending on the value of at least one of said at least two physical properties. However, the disclosed system does not contain means to adjust temperature of the wet mortar.
Thus, there is a need for new and improved solutions that overcome the aforementioned disadvantages as far as possible.
It is an object of the present disclosure to provide improved solutions for preparing three-dimensional objects from curable binder compositions, especially curable mineral binder compositions, with an additive manufacturing process. In particular, a constant quality and properties of the curable binder composition is to be achieved during the whole process. Furthermore, blocking of the curable binder composition in the printing head should be avoided as good as possible.
Surprisingly, it was found that these objects can be achieved with the method according to at least one embodiment.
Specifically, according to the disclosure, a method for producing a three-dimensional object from a curable binder composition with an additive manufacturing process, comprising the steps of:
As it turned out, on-line measurement and/or adjustment of the temperature of the curable binder composition in the setting state before it reaches the printing head and/or in the printing head, i.e., in the mixing unit and/or in the supply line and/or in the printing head, allows a very efficient control of the quality and properties of the curable mineral binder composition, which results in improved quality the 3D printed object. Especially, the temperature of the curable binder composition can be adjusted using commonly available temperature control means, including temperature sensors, heat exchanger devices, and control units.
Especially, knowing the measured temperature of the curable binder composition in the printing head in real time is highly beneficial because deviations from target values can be identified and controlling actions can be initiated to keep the temperature within the range of target values and/or stopping the manufacturing process. Deviations may for example be caused by fluctuations of raw material quality and/or temperature, by operator errors and/or by temperature of the surroundings.
Overall, the inventive method is useful to produce high quality printed three-dimensional objects. Especially, it drastically increases the safety of the additive manufacturing process because any issue with regard to temperature of the curable binder composition flowing through the process can be instantaneously detected and directly be solved. In case of potential danger, it is for example possible to stop the application before the printed object collapses due to too weak bonding between the applied layers or before the printing head is blocked because, for example, of too high viscosity of the curable binder composition resulting from altered curing reactions.
Compared to known solutions based on the measurement of physical parameters, such as density and viscosity, of the curable binder composition, the inventive approach has turned out to provide an improved solution to control the process and the quality the 3D printed object.
Further aspects are described below and are subject of the further independent claims. Particularly preferred embodiments are outlined throughout the description and the dependent claims.
A first aspect of the present disclosure is directed to a method for producing a three-dimensional object from a curable binder composition, especially curable mineral binder composition, with an additive manufacturing process, comprising the steps of:
A “curable binder composition” stands for a material which is typically flowable or liquefiable and which, after mixing, for example by the addition of mixing water, or by the mixing of components or by heating, can cure by a chemical reaction to form a solid. For example, these are reaction resins, mineral binders, mineral binder compositions or mixtures thereof.
In particular, reactive resins are liquid or liquefiable synthetic resins that cure by polymerization or polyaddition to form duromers. For example, unsaturated polyester resins, vinyl ester resins, acrylic resins, epoxy resins, polyurethane resins and/or silicone resins can be used.
Especially preferred, the curable binder composition is a curable mineral binder composition.
The term “mineral binder” refers in particular to a binder which reacts in the presence of water in a hydration reaction to form solid hydrates or hydrate phases. This can be, for example, a hydraulic binder (e.g. cement or hydraulic lime), a latent hydraulic binder (e.g. slag), a pozzolanic binder (e.g. fly ash) or a non-hydraulic binder (e.g. gypsum or white lime).
A “mineral binder composition” is accordingly a composition containing at least one mineral binder. In particular, it contains the binder, aggregates and optionally one or more additives. Aggregates may be, for example, aggregates, gravel, sand (in natural and/or processed (e.g. crushed) form) and/or filler. The mineral binder composition is in particular a fluid binder composition mixed with mixing water.
In particular, the mineral binder or the binder composition contains a hydraulic binder, preferably cement. Particularly preferred is a cement with a cement clinker content of 35% by weight, in particular the cement is of type CEM I, II, III, IV or V, preferably cement of type CEM I (according to standard EN 197-1). A proportion of the hydraulic binder in the total mineral binder is advantageously at least 5% by weight, in particular at least 20% by weight, preferably at least 35% by weight, in particular at least 65% by weight. According to a further advantageous embodiment, at least 95% by weight of the mineral binder consists of hydraulic binder, in particular cement clinker.
However, it can also be advantageous if the binder composition comprises other binders in addition to or instead of a hydraulic binder. These are in particular latent hydraulic binders and/or pozzolanic binders. Suitable latent hydraulic and/or pozzolanic binders are, for example, slag, granulated blast furnace slag, fly ash and/or silica fume. Likewise, the binder composition may include inert materials such as limestone powder, quartz powder and/or pigments. In an advantageous embodiment, the mineral binder contains 5-95% by weight, in particular 5-65% by weight, more specifically 15-35% by weight, of latent hydraulic and/or pozzolanic binders.
The expression “the curable binder composition in the setting state” in particular means that the curable binder composition is in a condition in which the setting of the binder in the curable binder composition has started but is not yet complete.
In case of mineral binder compositions, the compositions are in the setting state after mixing the mineral binder and optionally further components, such as e.g. aggregates, with the mixing water.
The three-dimensional object produced by the process according to the disclosure can have almost any desired shape and can, for example, be a finished part for a structure, e.g. for a building, a masonry structure and/or a bridge.
The additive manufacturing process according to the present disclosure is in particular a generative free space process. This means that the three-dimensional object is formed layer by layer, namely by applying curable material only at those points where the three-dimensional object is to be formed. In the case of overhangs and/or cavities, a support structure can optionally be provided. In contrast, in powder bedding or liquid processes, for example, the entire space is typically filled, and the material is then selectively solidified at the desired locations.
Free-space processes have proved to be particularly advantageous in connection with the production of three-dimensional objects from a curable binder composition.
Preferably, the curable binder composition is produced in the setting state by mixing of the constituents of the curable binder composition in a mixing unit. Most preferably, the curable binder composition is continuously produced in the setting state, especially during the application of the curable binder composition.
For conveying the curable binder composition in the setting state via a supply line to a printing head, the additive manufacturing device comprises in particular a conveying device, particularly a pump, with which the curable binder composition can be conveyed to the printing head via the supply line.
The supply line can have a length of, for example, 50 cm to 100 m, especially 2 m to 50 m.
For applying the curable binder composition in the setting state, the printing head is in particular controlled on the basis of a structural data model of the three dimensional object. The structural data model may be stored in a memory module of a control unit of the additive manufacturing device.
Preferably, determining a temperature of the curable binder composition in the mixing unit and/or in the supply line and/or in the printing head, takes place simultaneously with the production of the curable binder composition, the conveying of the curable binder composition in the setting state via the supply line, and the application of the curable binder composition. This allows for a real time measurement and adjustment of the temperatures. Particularly, the real time measurement of temperatures enables automatic adjustment of the temperature of the curable binder composition in the printing head by controlling the temperature of the curable binder composition in the mixing unit and/or the supply line. The temperature control can be conducted manually and/or automatically using a feedback controller.
The expression “adjusting temperature of a composition” means in the context of the present disclosure that temperature of the composition is actively kept within a range of target values by using heat exchanging means, such as one of more heat exchanger devices.
Generally, adjusting the temperature of a composition can be conducted directly and/or indirectly. For example, a heat exchanger can be used to adjust the temperature of at least one of constituents of the curably binder composition before adding it/them to the mixing unit to provide the curable binder composition in the setting state. Alternatively or in addition, the temperature of the curable binder composition in the setting state can be directly adjusted using a heat exchanger device arranged, for example, to the mixing unit or the supply line.
The term “heat exchanger device” refers in the present disclosure to devices that are used to exchange heat between same or different forms of material through conduction, convection, or radiation. Suitable heat exchanger devices include, for example, heat exchangers that exchange heat between two fluids having different temperatures without physical mixing of the fluids as well as coolers and heaters comprising, for example, a heating/cooling element configured to exchange heat between the element and the surrounding fluid.
Particularly, a heat exchanger device typically contains temperature sensors and control units that enable automatic control of a process variable, such as the temperature of the fluid to be heated/cooled, by adjusting one or more manipulated variables, such as the flow rate and/or inlet temperature of the heat exchanging medium.
Main types of heat exchangers include double-tube heat exchanger, shell-and-tube heat exchanger, and plate heat exchanger. Heat exchangers can also be classified based on their flow arrangement into parallel-flow, counter-flow, and cross-flow heat exchangers.
A double-tube heat exchanger consists of two concentric tubes where one fluid flows though the inner tube and the other fluid flows into the annular gap between the inner and outer tubes. A shell-and-tube heat exchanger consists of a shell, typically a large pressure vessel, and a bundle of tubes inside it. One fluid runs through the tubes, and another fluid flows over the tubes. A plate heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between two fluids.
Further suitable heat exchanger devices include thermoelectric coolers and heaters that use the Peltier effect to create a heat flux at the junction of two different types of materials. Such devices are also known as Peltier devices, Peltier heat pumps, solid state refrigerators, or thermoelectric coolers.
According to one or more preferred embodiments, the temperature of the curable binder composition in the mixing unit is adjusted, preferably by cooling, using a heat exchanger device arranged to the mixing unit.
The heat exchanger device arranged to the mixing unit preferably comprises a jacket, preferably a metallic jacket, surrounding at least a portion of the mixing unit. The metallic jacket preferably comprises inner and outer walls enclosing a plurality of canals for a heat exchanging medium. The jacket furthermore comprises at least one inlet and outlet for the heat exchanging medium, for example a liquid. The jacket may further comprise one or more fins arranged on the inner surface of the jacket to increase the heat exchanging area between the heat exchanging medium and the mixing unit.
According to one or more preferred embodiments, the curable binder composition in the setting state is supplied via a supply line to the printing head, preferably using a pump, and a temperature of the curable binder composition in the supply line, preferably downstream of the pump, is adjusted, preferably by cooling, using a heat exchanger device arranged to the supply line.
There are no particular restrictions for the type of the heat exchanger device arranged to the supply line. According to a preferred implementation, the heat exchanger device is a shell and tube heat exchanger or a tubular heat exchanger, preferably a double tube heat exchange, preferably having a length of 0.25-5 m, more preferably 0.5-3 m.
In case of a double tube heat exchanger, the outer tube has an outer diameter of, for example, 40-100 mm, especially 45-85 mm and/or the inner tube has an inner diameter of, for example, 20-65 mm, especially 25-50 mm.
In one preferred implementation, the heat exchanger device arranged to the supply line is the double tube heat exchanger and the curable binder composition in the setting state is arranged to flow thought the inner tube of the heat exchanger and the heat exchanging fluid flows through the space between the inner and outer tubes. The flow arrangement of the double tube heat exchanger can be parallel-flow or counter-flow, wherein counter-flow may be preferred in terms of heat transfer efficiency.
The heat exchanger device is preferably arranged in the vicinity of the pump, wherein the inlet of the heat exchanger device for the curable binder composition is preferably no further than 5 m, more preferably not more than 2.5 m, even more preferably not more than 1.5 m, from the outlet of the pump.
According to one or more embodiments, the curable binder composition comprises a first component comprising mineral binder and aggregate, a second component comprising water, and optionally at least one third component comprising one or more additive(s), wherein the temperature of the second and/or third component is adjusted before adding it/them to the mixing unit, preferably by cooling, using a heat exchanger device.
The additive in particular, is an additive for controlling the chemical and/or physical properties of the curable binder composition. Preferably, the additive is selected from an accelerator, a retarder, a rheological aid and/or a superplasticizer. Particularly, the additive is an additive for mineral binder compositions.
It may be preferred to add the components of the curable binder composition to the mixing unit as separate feeds. However, it can also be preferred to form a premix of the third and/or any further component comprising one or more additive(s) with the first and/or the second component before adding them to the mixing unit. This can be helpful to obtain a more precise dosing of the additives, which usually are added with rather low proportions.
Preferably, the components of the curable binder composition are added to the mixing unit from containers each containing one component of the curable binder composition. The containers can be directly connected to the inlets of the mixing unit via one or more feed lines. However, in one or more preferred implementations, the components are added to the mixing unit using a feed device comprising individually controllable supply units, such as powder dosing device(s) and/or liquid dosing device(s), that enable a metered addition of the materials. If a feed device is used, it is preferably connected via the feed lines to the containers and to the inlets of the mixing unit via further feed line(s).
Thereby, the proportion of the first component particularly can be controlled with a first supply unit, for example with a powder dosing device. A powder dosing device may comprise a controllable valve and a balance for weighing the weight of powder introduced into the mixing unit.
Alternatively or in addition, the proportion of the second component, i.e., water, introduced to the mixing unit can be adjusted with another supply unit, for example, a controllable liquid dosing device. For example, the liquid dosing device comprises a valve with a flow meter to measure the amount of water introduced into the mixing unit.
Likewise, the proportion(s) of the third and/or any further component(s) added to the mixing unit can be adjusted with additional supply unit(s), for example, controllable liquid dosing device(s), particularly comprising a valve with a flow meter to measure the amount of additive introduced into the mixing unit.
However, it is also possible to add one or more of the components at a constant rate into the mixing unit, whereas the proportion(s) of the other component(s) is/are controlled as described above.
The temperature an individual component of the curable binder composition before addition to the mixing unit can, therefore, be adjusted in the container of the component and/or in the feed line connecting the container to the feed device or mixing unit and/or in the further feed line connecting the feed device to the mixing unit.
The preferred type of the heat exchanger device used for adjusting the temperature of a component depends mainly on the arrangement, i.e., whether the heat exchanger device is arranged to a container or a feed line. Suitable heat exchanging devices for containers include, for example, coil heat exchangers and air- and water-cooled chillers.
Suitable heat exchanger devices to adjust the temperature of a component in a feed line include heat exchangers, especially double-pipe, shell-and-tube, and plate heat exchangers as well as thermoelectric coolers and heaters, particularly Peltier devices.
In a preferred implementation, the temperature of the second and/or third component before adding it to the mixing unit is adjusted using a heat exchanger arranged to a feedline connecting a container containing the component to mixing unit or a feed device.
According to one or more embodiments, one or more additives for controlling the chemical and/or physical properties of the setting curable binder composition is/are added to the setting curable binder composition in the printing head and/or in the supply line.
These one or more additive(s) can be the same as the one or more additive(s) comprised in the optional third and/or any further component described above, or they are different.
Thus, in this case, the additive is added to the curable binder composition in setting state downstream the mixing unit. This allows, for example, for adjusting the properties of the curable binder composition right before application, for example, in the printing head. Thereby, for example, the consistency and/or rheology of the curable binder composition can be adjusted for proper extrusion and/or layer buildup.
The additive preferably is a substance capable of controlling and/or modifying the flow properties and/or the setting behavior of the curable binder composition. Preferably, the additive is selected from an accelerator, a retarder, a rheological aid and/or a superplasticizer. Particularly, the additive is an additive for mineral binder composition.
According to one more embodiments, the temperature of the at least one additive is adjusted before adding to the printing head and/or to the supply line, preferably by cooling, using a heat exchanger device.
Particularly, the at least one additive is added to the printing head and/or the supply line via an additive supply device, optionally with an additive inlet nozzle. Furthermore, the additive supply device is preferably connected to an additive reservoir via an additive feed line. The additive supply device and/or the additive inlet nozzle preferably are controllable, particularly with the control unit.
The temperature of the additive can then be adjusted in the additive reservoir and/or the additive feed line.
The preferred type of the heat exchanger device depends mainly on the arrangement, i.e., whether the heat exchanger device is arranged to the additive reservoir or to the additive feed line. Suitable heat exchanger devices for containers and feed lines have already been discussed above in the context of the temperature control of the second and third components of the curable binder composition.
In a preferred implementation, the temperature of the at least one additive before adding to the to the printing head and/or to the supply line is adjusted using a heat exchanger arranged to an additive feed line connecting an additive supply device to an additive reservoir.
According to one or more embodiments, the method comprises the steps of:
In the at least one dynamic mixer, the stirring element is configured for mechanically mixing the curable binder composition, and optionally the one or more additive(s). The stirring element comprises for example one or more stirring shaft(s) and/or stirring blade(s).
Particularly, the at least one dynamic mixer is arranged between a printing head outlet, especially an outlet nozzle, and the end of the section of the supply line in which the pump has been arranged. Especially, the at least one dynamic mixer is arranged between the printing head outlet, especially an outlet nozzle, and the additive supply device, if the latter is present. Particularly preferred, the at least one dynamic mixer is arranged in the printing head.
According to one or more preferred embodiments, the temperature of the curable binder composition in the mixing unit and/or in the supply line and/or of at least one of the constituents of the curable binder composition before adding it/them into the mixing unit (10) is adjusted such that the temperature of the curable binder composition in the printing head and/or in the printing head outlet is within a pre-determined range of target values for the temperature. This can be done manually and/or automatically.
Especially preferred, the temperature of the curable binder composition in the mixing unit and/or in the supply line is automatically adjusted with a control unit such that the temperature of the curable binder composition in the printing head and/or in the printing head outlet is within a pre-determined range of target values for the temperature.
A pre-determined range of target values is preferably stored in the memory module of the control unit. The pre-determined range of target temperature values in particular comprises at least a lower limit and an upper limit. These limits may be identical. In this case the pre-determined range of target values equal a single pre-determined temperature value.
Automatically adjusting the temperature of the curable binder composition in the mixing unit and/or in the supply line is preferably effected with a control loop with one or more control elements, such as a control device for a heat exchanger device, for example, arranged to the mixing unit and/or supply line, which control elements are controlled based on the measured temperature of the curable binder composition in the printing head.
The control loop may for example be implemented in the form of a proportional-integral controller (PI controller) or in the form of a proportional-integral-derivative controller (PID controller).
In this way, the temperature of the curable binder composition in setting state in the printing head can be automatically held constant within desired ranges.
A further aspect of the present disclosure is directed to a system for producing a three-dimensional object from a curable binder composition with an additive manufacturing process having means adapted to execute the steps of the method as described above.
Especially, a system for producing a three-dimensional object from a curable binder composition with an additive manufacturing process, especially for performing the method as described above, comprises:
Features described above in connection with the inventive method are preferably implemented likewise in the inventive system.
Especially, the system comprises one or more containers for the constituents of the curable binder composition produced in the mixing unit. The containers are especially connected to the inlets of the mixing unit via one or more feed lines.
Furthermore, the system preferably contains a feed device comprising one or more individually controllable supply units, especially one or more powder dosing device(s) and/or one or more liquid dosing device(s). A powder dosing device may comprise a controllable valve and a balance for weighing the weight of powder introduced into the mixing unit. For example, the liquid dosing device comprises a valve with a flow meter to measure the amount of liquid, for example water, introduced into the mixing unit. The one or more supply unit(s) are controllable, preferably with the below described control unit.
In a further preferred embodiment, the system further comprises:
Furthermore, the additive supply device is preferably connected to an additive reservoir via an additive feed line. The additive supply device and/or the additive inlet nozzle preferably are controllable, particularly with the below described control unit. According to one or more embodiments, the system further comprises:
According to one or more embodiments, the system further comprises:
The stirring element preferably comprises for example one or more stirring shaft(s) and/or stirring blade(s).
Especially, the system comprises a control unit for controlling the additive manufacturing process of the three-dimensional object. The control unit preferably comprises a processor module, a memory module for storing data and one or more interface module(s) especially for sending and/or receiving data to/from individual components of the system, especially to/from the measuring unit(s), the heat exchanger devices, the constituent supply device(s), the additive supply device, the dynamic mixer, the printing head and/or the movement device for moving the printing head.
Preferably, the memory module comprises a memory area in which a three-dimensional model of the three-dimensional object to be manufactured and/or target values are stored.
According to one or more embodiments, the control unit is configured to:
Particularly, the control unit is configured to:
Preferably, the control unit is configured to automatically control the temperature of the curable binder composition in the mixing unit and/or in the supply line and/or the temperature of at least one of the constituents of the curable binder composition before adding them into the mixing unit such that:
The target values for the temperature are preferably stored in the memory module of the control unit.
Another aspect of the present disclosure is directed to a computer program comprising instructions to cause the system as described above to execute the method as described above. The computer program may for example be present on a portable data carrier, stored on a computer system, stored on a server and/or stored in a control unit of an additive manufacturing device.
Further advantageous implementations of the disclosure are evident from the exemplary embodiments.
The drawings used to explain the embodiments show:
The system 1 comprises a movement device 2 with a movable arm 2.1. A printing head 3 is attached to the free end of the arm 2.1, which can be moved by the arm 2.1 in all three spatial dimensions. Thus, the printing head 3 can be moved to any position in the working area of the movement device 2.
Inside, the printing head 3 has a tubular passage 3.1 passing through from the end face facing the arm 2.1 (at the top in
The printing head 3 comprises an additive supply device 5 consisting of a pump and an inlet nozzle, which opens into passage 3.1. Through the inlet nozzle of the additive supply device 5, an additive, for example a rheological aid or an accelerator, can be added to the curable binder composition flowing through the passage 3.1. Optionally, the printing head 3 may comprise supply devices for adding one or more further additives.
Furthermore, inside the printing head 3, downstream with respect to the additive supply device 5, a dynamic mixer 6 is arranged in the passage 3.1, which additionally mixes the curable binder composition and the additive. The dynamic mixer comprises a drive unit 6.1, which is configured for powering a stirring shaft 6.2 for mechanically mixing the curable binder composition and the additive.
The system 1 for applying a curable binder composition also has a feed device 9 which is connected on the input side to three containers 11.1, 11.2, 11.3 and an additive reservoir 11.4 via feed lines. Each of the three containers 11.1, 11.2, 11.3 contains one component of the curable binder material. The first component, which is present in the first container 11.1, is for example a dry mineral binder composition, for example a cement or a dry mortar. The second component, which is present in the second container 11.2, consists of water, for example. The third component present in the third container 11.3 is, for example, a superplasticizer in the form of a polycarboxylate ether. The additive reservoir 11.4 contains, for example, a rheological aid and/or accelerator, for example modified cellulose and/or a microbial polysaccharide.
On the output side, the feed device 9 has three separate outlets, each of which is connected to one of three inlets 10.1, 10.2, 10.3 of a mixing unit 10. The feed device 9 also contains individually controllable constituent supply devices, for example powder dosing device(s) and/or one or more liquid dosing devices (not shown in
The powder dosing device for example comprises a controllable valve and a balance for weighing the weight of powder introduced into the mixing unit 10. A liquid dosing device for example comprises a valve with a flow meter to measure the amount of water or plasticizer introduced into the mixing unit
A further outlet (not shown in
The feedlines connecting the containers 11.2 and 11.3 to the feed device 9 are equipped with heat exchanger devices 13.3 and 13.4 to adjust the temperature of the components of the curable binder material before feeding them to the mixing unit 10. The feedline connecting the additive reservoir 11.4 to the feed device 9 also contains a heat exchanger device 11.4 to adjust the temperature of the additive before feeding it to the mixing unit 10 and/or to the printing head 3.
The mixing unit 10 is designed as a dynamic mixer and comprises, in addition thereto, an integrated conveying device in the form of a screw conveyor. In the mixing device, the individually metered components are mixed together and conveyed into the flexible supply line 12 attached to the outlet side of the mixing unit 10. In operation, the mixing and conveying of the curable binder composition can take place continuously.
The curable binder composition in the setting state can be conveyed into the printing head 3 via the flexible supply line 12, which opens into the tubular passage 3.1, and continuously applied through the printing head outlet 4.
Another heat exchanger 13.1 is arranged to the mixing unit 10 to adjust the temperature of the curable binder composition before feeding it to the flexible supply line 12. The heat exchanger device 13.1 preferably comprises a jacket surrounding at least a portion of the mixing unit. The jacket can comprise inner and outer walls enclosing a plurality of canals for a heat exchanging medium and at least one inlet and outlet for the heat exchanging medium, for example a liquid.
For conveying the curable binder composition in the setting state via a supply line 12 to a printing head 3, the system further comprises a pump 7, with which the curable binder composition can be conveyed to the printing head 3 via the supply line 12.
A heat exchanger device 13.2 is arranged to the supply line, in the vicinity of the pump 7, to adjust the temperature of the curable binder composition in the setting state before feeding it to the printing head 3. The heat exchanger device 13.2 is preferably a shell and tube heat exchanger or a tubular heat exchanger, preferably a double tube heat exchange.
Furthermore, temperature sensors 15.1, 15.2, and 15.3 are integrated in the mixing unit 10, the supply line 12, and the printing head 3, respectively.
A central control unit 16 of the system 1 includes a processor module, a memory module, and a plurality of interfaces for receiving data and a plurality of interfaces for controlling individual devices of the system 1.
In this regard, the mixing unit 10 is connected to the control unit 16 via a first control line 17a, while the feeding device 9 is connected to the control unit 16 via a second control line 17b. As a result, the individual components in the containers 11.1, 11.2, 11.3 can be metered into the mixing unit 10 via the control unit 16 in accordance with predetermined recipes stored in the control unit 16 and the thus obtained curable binder composition in the setting state can be conveyed into the supply line 12 at an adjustable conveying rate.
The additive supply device 5 is connected to the control unit 16 via a separate control line 17k and can be controlled or monitored by the control unit 16.
The movement device 2 is also connected to the control unit 16 via a further control line 17g. This means that the movement of the printing head 3 can be controlled via the control unit 16.
Similarly, the temperature measuring devices 15.1, 15.2, and 15.3 are connected to the control unit 16 by control lines 17c, 17d, and 17e so that data recorded in the temperature measuring devices 15.1, 15.2, and 15.3 can be transmitted to the control unit 16.
The dynamic mixer 6 in the printing head 3 can be controlled via control line 17j.
The heat exchanger devices 13.1, 13.2, 13.3, 13.4, and 13.5 are connected to the control unit 16 by control lines (not shown in
Furthermore, the control unit 16 is connected via control line 17h with an interface unit 8 having a user interface that allows for controlling the system 1 and displaying data.
The control unit 16 is thereby configured, for example, in such a way that:
| Number | Date | Country | Kind |
|---|---|---|---|
| 23171554.1 | May 2023 | EP | regional |
