WO2024078993A1

WO2024078993A1 - Wax formwork production device and method for producing a wax formwork

Info

Publication number: WO2024078993A1
Application number: PCT/EP2023/077722
Authority: WO
Inventors: Sven JONISCHKIES; Norman Hack; Harald Kloft; Mainka Jeldrik; Rolf DIESSLIN
Original assignee: Technische Universität Braunschweig; Herrhammer Gmbh Spezialmaschinen
Priority date: 2022-10-11
Filing date: 2023-10-06
Publication date: 2024-04-18
Also published as: DE102022126252A1

Abstract

The invention relates to a wax formwork production device for producing a wax formwork (150) for concrete casting, having: (a) a melting unit (10) for heating the wax to a predetermined temperature above the solidification temperature of the wax, (b) a mixing unit (20) which is configured to admix gas into the wax such that a wax-gas mixture is produced, (c) a nozzle (30) which is arranged downstream of the mixing unit (20) in the direction of flow and is configured to apply the wax-gas mixture in layers to a substrate, (d) a positioning system (50) for positioning the nozzle (30) relative to the substrate, and (e) a control unit (60) which is designed to control the positioning system (50) for positioning the nozzle (30) relative to the substrate such that the wax formwork (150) is produced. The invention also relates to a concrete casting manufacturing plant having such a wax formwork production device and a concrete feeding device for casting concrete in the wax formwork, to a method for producing a wax formwork, and to a method for producing a concrete component.

Description

Wax formwork manufacturing device and method for manufacturing a wax formwork

The invention relates to a wax formwork manufacturing device for producing a wax formwork for concrete casting. According to a second aspect, the invention relates to a method for producing a wax formwork for concrete casting. Furthermore, the invention relates to a concrete casting part manufacturing plant and a method for producing a concrete component.

Waxes include both natural waxes and industrially manufactured waxes. These include animal waxes, vegetable waxes, mineral waxes, petroleum waxes and synthetic waxes. Waxes are usually malleable at 20°C, solid to brittle, coarse to fine crystalline, translucent to opaque, but not glassy, melt above 40°C without decomposition, have a relatively low viscosity even slightly above the melting point, are highly temperature-dependent in terms of consistency and solubility and can be polished under light pressure.

A formwork is a surface-sealing component that serves as a support for the concrete until it hardens, usually a temporary component that enables concrete parts to be manufactured in the desired shape within the selected manufacturing tolerances. The manufacture of precise, free-form concrete components usually requires special formwork. These are usually made of wood, acrylonitrile-butadiene-styrene copolymers (ABS), polylactide (PLA), polyvinyl alcohol (PVAL or PVOH), polyurethane (PU) or polystyrene (PS). In most cases, the formwork material can be used due to a required coating cannot be recycled. In addition, the tolerance deviations of most special formwork for the production of precision finished parts are not satisfactory.

The object of the present invention is to avoid disadvantages in the prior art.

The invention solves this problem by a wax formwork manufacturing device for producing a unit for heating the wax to a predeterminable temperature above a solidification temperature of the wax, (b) a mixing unit which is designed to mix gas into the wax so that a wax-gas mixture is formed, (c) a nozzle which is arranged downstream of the mixing unit in the flow direction and is designed to apply the wax-gas mixture to a substrate in layers, (d) a positioning system for positioning the nozzle relative to the substrate and (e) a control unit which is designed to control the positioning system for positioning the nozzle relative to the substrate so that the wax formwork is formed.

The invention is based on the finding that the gas inclusions in a wax formwork made from a wax-gas mixture mean that the wax formwork shrinks less during and after production and therefore also has less warping. In other words, the dimensional stability of the wax formwork can be very high. The gas inclusions also mean that the wax formwork is heated less due to the thermally insulating effect of the gas inclusions when the wax formwork is exposed to the hydration heat of the concrete during the production of a concrete component. This also promotes the strength of the wax formwork during the production of the concrete component. Another advantage is that the material consumption of wax is reduced by using a wax-gas mixture.

Another advantage is that the wax formwork is ecological and at the same time very economical due to the reusability of the wax by melting it down. The wax formwork produced with the wax formwork production device according to the invention has no cracks or cavities They are also very stable, making the wax formwork particularly suitable for the production of concrete components made of ultra-high-performance concrete (IIHPC).

A substrate is understood to be a base plate, a deposited wax-gas mixture or a base body to be printed on. A gas is understood to be a pure substance, in particular carbon dioxide, or a gas mixture, in particular air.

The glass transition temperature of the wax is preferably above 40 °C. The solidification temperature of the wax is preferably above 50 °C, particularly preferably above 60 °C. The solidification temperature can be determined according to DIN ISO 2207.

Preferably, the compressive strength of the wax at 20°C is more than 0.25 N/mm ² . Advantageously, the compressive strength of the wax-gas mixture at 20°C is at least half the compressive strength of the wax at 20°C. Preferably, the elastic modulus of the wax under compressive load at 20°C is more than 25 N/mm ² , preferably more than 500 N/mm ² , in particular more than 1000 N/mm ² , particularly preferably more than 2000 N/mm ² . Preferably, the dropping point of the wax is above 80°C, in particular above 150°C.

It can be provided that a wax can be used that consists of a renewable raw material. In particular, it can be provided that the wax exclusively comprises renewable raw materials. It is also conceivable that the wax consists of at least 50%, in particular 90%, preferably 100% of a renewable raw material. Renewable raw materials for the wax can be, for example, plant-based waxes such as soy wax, palm oil wax, coconut oil wax and/or rapeseed oil wax. The list is not to be understood as exhaustive.

Preferably, the gas and/or the wax-gas mixture contain a filler, in particular a mineral and/or organic filler. Alternatively or additionally, the mixing unit is designed to mix a filler, in particular a mineral and/or organic filler, into the wax and/or the wax-gas mixture. The filler can be, for example, Calcium silicate hydrate, calcium carbonate, limestone powder, talcum and/or raw cellulose can be used. The filler is selected in particular so that it increases the compressive strength of the wax-gas mixture and/or improves at least one thermal and/or mechanical material property of the wax-gas mixture.

Preferably, the melting unit has or forms a heating element, in particular in the form of a heating cartridge, a heating band, a heat exchanger, a continuous flow heater, a heating medium, an immersion heater or the like.

A further development of the invention provides that the melting unit is arranged in the mixing unit or upstream of the mixing unit in the direction of flow. If the melting unit is upstream of the mixing unit in the direction of flow, the melting unit preferably has an opening for receiving wax. If the melting unit is arranged in the mixing unit, the mixing unit preferably has an opening for receiving wax.

The mixing unit preferably has a gas inlet through which gas can be supplied. The gas inlet is preferably in fluid communication with a fan and/or a gas compressor. Alternatively or additionally, a nozzle is arranged at the gas inlet or the gas inlet forms this. The nozzle is preferably controllable. The nozzle is preferably connected to a pressure vessel that contains a compressed gas.

Preferably, a conveying hose is arranged between the melting unit and the mixing unit and/or between the mixing unit and the nozzle. Preferably, the conveying hose is heated. It is possible to arrange a conveying device on the conveying hose which is designed to support the conveying of the wax and/or the wax-gas mixture through the conveying hose. The conveying device can be, for example, a pump, an extruder or a compressor. Alternatively or in addition to this, the conveying of the wax can be supported by the pressure in the melting unit and/or in the mixing unit. It is also possible to arrange the melting unit and the mixing unit and/or the mixing unit and the nozzle in such a way that no conveying hoses are required. Preferably, the The melting unit is arranged in or above the mixing unit and the mixing unit is arranged above the nozzle, so that the conveying of the wax and/or the wax-gas mixture is supported by gravity and no conveying device is required. The melting unit, the mixing unit and the nozzle preferably have a common housing. The positioning system is preferably designed to accommodate the melting unit, the mixing unit and the nozzle and to position them together relative to the substrate. The control unit is preferably designed to control the positioning system for the joint positioning of the melting unit, the mixing unit and the nozzle relative to the substrate.

Preferably, the control unit is designed to adjust a mass flow of the nozzle. This is particularly advantageous if the speed of movement of the nozzle is changed relative to the substrate and at the same time the strand width of the wax-gas mixture extruded through the nozzle in strand form is to remain the same. In addition, the mass flow can be set to zero if the position of the nozzle is to be changed relative to the substrate without the wax-gas mixture being extruded at the same time. Preferably, the control unit is designed to control a conveying device such that the mass flow at the nozzle corresponds to a predeterminable mass flow.

A further development of the invention provides that the mixing unit has (a) a mixing chamber with a tempering surface, (b) a tempering device which is set up to temper the tempering surface to a tempering temperature so that the wax-gas mixture is tempered on the tempering surface of the mixing chamber, and (c) a scraping element for scraping the wax-gas mixture from a scraping wall of the mixing chamber and/or from the tempering surface of the mixing chamber. The scraping wall is preferably an outer wall of the mixing chamber. Preferably, the temperature of the wax and/or the wax-gas mixture does not fall below the solidification temperature of the wax during tempering. Alternatively, the temperature of the wax and/or the wax-gas mixture does not fall below a minimum temperature during tempering, which is preferably a maximum of 20 °C, preferably a maximum of 10 °C, in particular a maximum of 5 °C, particularly preferably a maximum of 2 °C below the solidification temperature of the wax. Preferably, the mixing chamber is rotationally symmetrical, in particular cylindrical. The mixing chamber can also have an open side, which is preferably designed to be closable.

The tempering surface preferably forms a scraping wall of the mixing chamber or part of a scraping wall of the mixing chamber. The scraping wall can in particular be an outer wall, a side wall and/or an inner wall of the mixing chamber. The tempering surface advantageously forms an outer wall of the mixing chamber or part of an outer wall of the mixing chamber. The mixing unit preferably has a tempering device that is arranged on the tempering surface or forms it. The melting unit is preferably the tempering device. Alternatively or additionally, the tempering device can be a heating element and/or a cooling element, in particular a heating medium, a coolant, a heating band, a heat exchanger or a heating cartridge. The scraping element is preferably arranged in the mixing chamber so as to be rotatable about an axis of rotation.

It can also be provided that the device has a 2-stage cooling system. In other words, the device can have a second tempering device in addition to the melting unit or the tempering device. It can be provided that the tempering device is also arranged in the mixing unit. It can be provided that the wax-gas mixture is first cooled down in the mixing unit by the tempering device. In particular, it can be provided that the tempering device in the mixing unit cools the wax to a temperature above a crystallization point. The crystallization point can be understood as the point at which a change from the amorphous liquid state of the mixture to the crystalline state occurs. In other words, the temperature of the mixture at the crystallization point is above the temperature of the solidification point and below the temperature of the dropping point. This has the advantage that improved transport from the tempering device in the mixing unit to the nozzle is possible and has sufficient stability to be able to be laid down in layers on top of each other. It can be provided that the second tempering device, which can be arranged in the nozzle, cools the wax-gas mixture down to the crystallization point.

For example, it can be provided that the wax is melted in the mixing unit and mixed with gas to form a wax-gas mixture and cooled down to a temperature above the crystallization point using the tempering device. The wax-gas mixture is then transported to the nozzle, among other things, where the wax-gas mixture is further cooled down in the nozzle. Preferably, the wax-gas mixture in the nozzle is cooled down to the crystallization point by the second tempering device. Optionally, the tempering device can also have a heating element so that the wax-gas mixture can be heated to the crystallization point. In particular, the temperature of the wax-gas mixture at the nozzle is set to the crystallization point using the second tempering device.

The scraping element is preferably designed as a mixing element that is set up to mix gas into the wax. Alternatively or in addition to this, a separate mixing element can be arranged in the mixing chamber. It is also possible to design the mixing unit without a mixing element.

Mixing a predefined amount of gas into the wax to create a wax-gas mixture can then be achieved, for example, by ensuring sufficient gas pressure in the mixing chamber.

The scraping element can be, for example, a stirring arm, which is preferably designed to correspond to the rotationally symmetrical and/or cylindrical mixing chamber. The outer diameter of the stirring arm preferably corresponds approximately to the inner diameter of the rotationally symmetrical and/or cylindrical mixing chamber.

Scraping means removing something from the surface by scraping or scraping it off. Part of the wax-gas mixture may remain as a residue on the surface. Preferably, a minimum distance between the scraping wall of the mixing chamber and the scraping element when the scraping element rotates about the axis of rotation is at most 1 mm, preferably at most 0.1 mm, particularly preferably at most 0.01 mm. Preferably, a maximum distance between the scraping wall of the mixing chamber and the scraping element when the scraping element rotates about the axis of rotation is at most 1 mm, preferably at most 0.1 mm, particularly preferably at most 0.01 mm. By keeping the distance as small as possible between the scraping wall of the mixing chamber and the scraping element when the scraping element rotates about the axis of rotation, it is ensured that as little wax-gas mixture as possible remains as residue on the scraping wall of the mixing chamber when the wax-gas mixture is scraped off.

The positioning system is preferably a robot, a gantry system or a combination of the robot and the gantry system. The robot and/or the gantry system preferably has at least three axes, preferably at least four, in particular at least five, particularly preferably six axes, particularly preferably at least seven axes. The positioning system preferably has a fastening device or a gripper which is designed to hold a nozzle and/or a tool for machining. The positioning system is preferably designed to automatically hold and/or automatically deposit the nozzle and/or the tool for machining.

A further development of the invention provides that the wax formwork production device has (a) a cooler which is arranged to cool the wax-gas mixture which has already been deposited, and/or (b) a warming device which is arranged to warm the wax-gas mixture which has already been deposited. A fan, a hose with air flowing through it and having an outlet opening, a heat radiator and/or an infrared radiator can be provided as a cooler and/or warming device.

Preferably, the cooler and/or the warming device can be aligned to a predeterminable angular position. The control unit is preferably designed to send a control signal to the cooler and/or the warming device so that the Cooling of the cooler and/or the warming device is changed such that the path of the cooler/or the warming device is in a position in which the nozzle will be after a certain period of time has elapsed after the control signal has been sent. Alternatively or additionally, the cooler and/or the warming device is arranged on a separate positioning system which is set up to move the cooler and/or the warming device into a position in which, in the direction of action of the cooler/or warming device, there is a position in which the nozzle will be after a certain period of time has elapsed. With a cooler, the deposited wax-gas mixture can be cooled so that it has sufficient solidity so that new wax-gas mixture can be applied to the deposited wax-gas mixture.

The deposited wax-gas mixture can be heated using a heating device, which is preferably present, so that sufficient adhesion of the newly applied wax-gas mixture to the already deposited wax-gas mixture is ensured. The already deposited wax-gas mixture is preferably not heated above the solidification temperature of the wax.

Preferably, the mixing unit is set up to add a predeterminable gas proportion to the wax. Particularly preferably, the control unit is set up to automatically carry out a method with the steps: (a) detecting a target gas proportion, (b) controlling the mixing unit so that when gas is mixed into the wax, a wax-gas mixture is formed with a gas proportion that corresponds to the target gas proportion. Preferably, the control unit detects the position of the nozzle relative to the substrate and detects the target gas proportion at this position. Alternatively or additionally, the control unit can read the large target gas proportion from a CAM file or a CAM program.

Preferably, the target gas proportion for the production of contour surfaces is lower than for the production of support structures. Contour surfaces are understood to be surfaces that come into contact with the concrete during the production of a concrete component. Support structures are understood to be structures that are located inside the component (infill) and/or do not come into contact with the concrete during the production of a concrete component. Preferably, the mixing unit has a Sensor for detecting the gas content of the wax-gas mixture. The control unit is preferably designed to control the mixing unit depending on sensor data. In particular, the mixing unit can be controlled by feedback of the sensor data.

Preferably, the control unit is configured to control the melting unit for heating the wax to a predeterminable temperature above a solidification temperature of the wax.

Preferably, the predeterminable gas proportion in the wax-gas mixture and/or the actual gas proportion in the wax-gas mixture is at least 10 vol.%, preferably at least 20 vol.%. Preferably, the predeterminable gas proportion in the wax-gas mixture and/or the actual gas proportion in the wax-gas mixture for the production of support structures is at least 20 vol.%, preferably at least 40 vol.%.

Preferably, the predeterminable gas proportion in the wax-gas mixture and/or the actual gas proportion in the wax-gas mixture for the production of contour surfaces is at most 40% by volume, in particular at most 30% by volume, particularly preferably at most 20% by volume.

A further development of the invention provides that the wax formwork manufacturing device has at least one tool for machining and the control unit is set up to (i) detect a machining path for machining the wax formwork and (ii) control the tool for machining so that machining of the wax formwork takes place. Machining can be carried out by milling, turning, drilling, grinding, cutting, eroding, honing and/or lapping, among other things. A milling cutter, a drill, a grinding wheel, a reamer or the like can be provided as a tool for machining. Preferably, the post-processing reduces a deviation of the wax formwork from a target model and/or adds and/or changes a deviating feature of the wax formwork. According to a further aspect, the invention solves the problem by a concrete casting production plant with a wax formwork production device according to the invention and a concrete feed device for pouring concrete into the wax formwork. The distance between the wax formwork production device and the concrete feed device is preferably at most 10 km, particularly preferably at most 1 km.

According to a further aspect, the invention solves the problem by a method for producing a wax formwork for concrete casting, comprising the steps of: (a) tempering the wax in a melting unit to a target temperature that is above a solidification temperature of the wax, (b) mixing gas into the wax in a mixing unit so that a wax-gas mixture is formed, and (c) applying the wax-gas mixture layer by layer to a substrate so that the wax formwork is formed. The layer-by-layer application of the wax-gas mixture to the substrate is preferably carried out automatically. Tempering is understood to mean heating, cooling or a combination of heating and cooling. For example, it may be advantageous to first heat the wax and/or the wax-gas mixture in a melting unit to a predeterminable temperature above a solidification temperature of the wax and then to cool the wax and/or the wax-gas mixture, wherein the temperature of the wax and/or the temperature of the wax-gas mixture does not fall below the solidification temperature of the wax.

Preferably, the method comprises the further step of mixing fillers, in particular mineral fillers, into the wax and/or into the wax-gas mixture.

A further development of the invention provides that the mixing of gas into the wax takes place at the same time as the tempering of the wax. At the same time means that the mixing of gas into the wax also takes place at at least one time during the tempering. The tempering of the wax preferably takes place at at least half of the times at which the mixing of gas into the wax takes place. Alternatively or in addition to this, the mixing of gas can also take place before and/or after the tempering of the wax. The method preferably comprises the additional step of scraping the wax-gas mixture from a tempering surface of the mixing unit using a scraping element. The tempering surface is a tempered surface of the mixing unit. The scraping element serves to scrape the wax-gas mixture from the tempering surface of the mixing chamber and can be designed as a stirring arm, for example.

Preferably, an application temperature of the wax-gas mixture when applying the wax-gas mixture to the substrate is a maximum of 35 °C, preferably a maximum of 20 °C, particularly preferably a maximum of 10 °C, especially preferably a maximum of 5 °C, most preferably a maximum of 2 °C below the solidification temperature of the wax. An application temperature that is below the solidification temperature of the wax ensures that the wax-gas mixture has sufficient strength. Alternatively or additionally, the application temperature of the wax-gas mixture when applying the wax-gas mixture to the substrate is a maximum of 10 °C, preferably a maximum of 5 °C, particularly preferably a maximum of 2 °C above the solidification temperature of the wax. An application temperature that is above the solidification temperature of the wax can be advantageous, in particular to improve the flowability and/or the adhesion properties of the wax-gas mixture when applying. It is advantageous to have the smallest possible deviation between the application temperature of the wax-gas mixture and the solidification temperature of the wax, as this minimizes the shrinkage of the wax-gas mixture after application and thus also the distortion of the wax formwork. The application temperature can take on different values at different locations and/or at different times, so that the application temperature can be temporarily above the solidification temperature and temporarily below the solidification temperature, particularly during the production process.

In a further development of the invention, the method comprises the additional step of machining the wax formwork by milling, turning, drilling, grinding, cutting, eroding, honing and/or lapping. A target model preferably contains a predetermined model of the wax formwork with all features and dimensions and, if necessary, information about the surface quality of certain surfaces. Preferably, the target model of the wax formwork is made available on a digital storage device. The digital storage device can be a hard drive, a USB stick, a memory card, a server or the like. Preferably, a control unit is set up to read this target model and to create a movement path for machining post-processing from it, so that the deviation of the wax formwork from the target model is reduced and/or a deviating feature of the wax formwork is added and/or changed. Alternatively or additionally, the target model itself contains a movement path for machining post-processing. Deviating features are features that distinguish the wax formwork before post-processing from the target model, for example holes, threads, fits, dimensional deviations or specified surface properties. Machining post-processing can also be used to smooth a surface, in particular a contour surface.

The method preferably comprises the additional steps: (a) cooling the wax formwork to room temperature and (b) heat treating at least one surface by tempering. Room temperature is understood to mean the temperature of a room in which the wax formwork cools. The room temperature is preferably more than 15 °C and less than 25 °C. Cooling can be carried out both actively and passively. For example, cooling can be carried out in the room air, in water, in another fluid and/or assisted by fans and/or coolants. Tempering is understood to mean that the wax formwork is heated after cooling to a tempering temperature that corresponds approximately to the glass transition temperature of the wax. This increases the crystallinity of the wax formwork. The deviation in amount of the tempering temperature from the glass transition temperature of the wax is preferably at most 10 °C, preferably at most 5 °C, particularly preferably at most 2 °C.

A further development of the invention provides for the coating of at least one surface. The coating can, for example, improve the surface quality and/or the hardness of the wax formwork. Plastic coatings with glass fiber reinforced plastic and/or polyurethane are particularly suitable for this purpose. According to a further aspect, the invention solves the problem by a method for producing a concrete component with the steps: (a) producing a wax formwork with the inventive method for producing a wax formwork for concrete casting, and (b) filling the wax formwork with concrete so that a concrete component is formed.

A further development of the invention provides for the melting out of a displacement body of the wax formwork from the concrete component. A displacement body is understood to be a partial structure of the wax formwork which is essentially enclosed within the concrete component after the concrete has been poured.

The method preferably comprises the further steps: (a) separating the wax formwork from the concrete component, and (b) refilling the wax formwork with concrete so that another concrete component is created. Preferably, the wax formwork can therefore be used to produce several concrete components, which preferably have a consistent dimensional stability. Alternatively or additionally, the wax formwork can be melted down and/or the wax from the wax formwork can be used as starting material for the production of a new wax formwork. This new wax formwork can have the same geometry as the previous wax formwork or a different one. It is also possible to use a wax and/or a wax mixture that contains a certain proportion of recycled wax when producing a wax formwork. Recycled wax is wax that has already been used to produce a wax formwork. Separation is understood to mean the non-destructive removal of the wax formwork or part of the wax formwork from the concrete component.

The method and device described above can also be used in particular for producing prototypes, unique items and/or small series. In particular, it can be provided that negatives are produced as wax molds for producing prototypes, unique items and/or small series. In other words, it can be provided that a so-called negative is produced as wax molds using the method and device. The prototype, unique item and/or small series can be produced based on the negative as wax molds. The method is also suitable for producing of prototypes on a scale of 1:1 as a positive. This means that the prototype is produced directly using the process or device. The process is particularly suitable for producing prototypes on a scale of 1:1. Such prototype production can be used in particular in the areas of aerospace, the automotive industry, ship and boat building for individual components and hull construction and/or in the packaging industry for formwork as a negative model for papier-mâché. The list is not to be understood as exhaustive.

Furthermore, the method and device described above can be used not only for the production of formwork for concrete components, but also for the production of formwork from elastomers, clay, mycelia, aerogels, resins (epoxy resin, polyurethane resin, polyester resin), silicone rubber, gypsum, plastics, ceramics, biopolymers, bacterial biocements and/or papier-mâché. The list is not to be understood as exhaustive.

Furthermore, the method and device described above can also be used to produce repair parts or replacement parts. It can be provided that the method and/or device are used in manual operation. This means that at least the nozzle is controlled manually.

For example, the position of the nozzle is set manually. It is also conceivable that the nozzle is moved manually during the extrusion of the wax-gas mixture and the area to be applied is specified manually. This has the advantage that the device and/or the method can also be used to repair or touch up defects. This has the particular advantage that the surface to be repaired does not have to be taught and a distance to be traveled does not have to be specified based on the surface. In particular, defects and/or flaking of the wax formwork can be repaired in this way.

Furthermore, it can be provided that the device has a displacement unit. The displacement unit can introduce a displacement body into the area to be printed in a step which takes place either before the extrusion of the wax-gas mixture or during the extrusion of the wax-gas mixture. The displacement body causes the material to be printed in a space which is defined by the displacement body is formed, no wax-gas mixture can be extruded and/or expansion of the extruded wax-gas mixture into the space can be avoided. In particular, it can be provided that the displacement body is removable. It is preferably provided that the displacement body can be removed by heating. It is advantageous if the displacement body can be removed without leaving any residue. For example, it can be provided that the displacement body evaporates when heated and the gases produced diffuse through the concrete or the material that is poured into the wax component. In particular, it is provided that the wax mold with the displacement bodies is first printed and then the material is poured into the wax mold. It can be provided that the removal of the displacement body and/or the displacement bodies takes place after the material has been poured into the mold.

This has the advantage that material can be saved by inserting displacement bodies, as the displacement bodies form a hollow space. In addition, the displacement bodies can also be inserted in such a way that the space is kept free for built-in components such as cables, power cables, sockets or similar. The count is not to be understood as exhaustive.

In the combination of 3D printing technologies and the precast concrete industry, displacement bodies can be printed from the wax-gas mixture, which are prefabricated before concrete 3D printing or are printed in the 3D printing process at the same time as concrete printing.

These displacement bodies can be installed in concrete components where, from a static point of view, no concrete is necessary in order to save concrete material.

In both cases, the wax is melted out of the concrete component if possible, creating a cavity that can then be used for built-in components.

Removal can be done by melting, for example. It is also conceivable that the displacement bodies are made of a biodegradable material. It can also be planned that the displacement bodies are etched out. It would be conceivable to introduce the wax foam inside a concrete component in order to absorb vibrations. In particular, it can be provided that a further body is arranged inside the displacement body in the space formed by the displacement body. The displacement body can consist of a material that can be selectively removed so that only the displacement body is removed but not the vibration body in the displacement body. For example, the vibration body in the displacement body can be made of concrete and/or the wax foam is left in the concrete component as a vibration body to absorb vibrations. The vibration body can, for example, have the shape of a sphere, but is not limited to this.

These vibrating bodies could in particular absorb vibrations. It would be conceivable to use such vibrating bodies in components that are used in earthquake zones.

The invention is explained in more detail below with reference to the accompanying drawings.

Figure 1 is a schematic view of a wax formwork manufacturing device according to the invention for producing a wax formwork for concrete casting,

Figure 2 is a schematic view of a positioning system of a wax formwork manufacturing device with a tool for machining,

Figure 3 is a schematic partial sectional view of an embodiment of a mixing unit in a wax formwork manufacturing device and

Figure 4 is a schematic partial sectional view of another embodiment of a mixing unit in a wax formwork manufacturing apparatus.

Figure 1 shows a schematic view of a wax formwork manufacturing device according to the invention, which comprises a melting unit 10, a mixing unit 20, a nozzle 30 and a positioning system 50. The melting unit 10 has a wax inlet 11 on the top, through which wax can be fed to the melting unit 10.

In the melting unit 10 there is a heating element (not shown), for example in the form of a heating cartridge, a heating band, a heat exchanger, a continuous flow heater, a heating medium, an immersion heater or the like. In the melting unit 10 the wax is heated to a predeterminable temperature above a solidification temperature of the wax. It is then conveyed to the mixing unit 20 via a conveying hose 110. The mixing unit 20 has a gas inlet 26 through which a gas can be supplied to the mixing unit 20. The gas can be a gas, in particular carbon dioxide, or a gas mixture, in particular air. In the mixing unit 20 the gas is mixed into the wax so that a wax-gas mixture is formed.

From the mixing unit 20, the wax-gas mixture is conveyed via a conveying hose 110 to a conveying device 100. The conveying device 100 can be designed as a pump, extruder or compressor. From the conveying device 100, the wax-gas mixture is conveyed via another conveying hose 110 to a nozzle 30. The wax-gas mixture is applied to a substrate in layers through the nozzle, so that a wax formwork is created.

It can also be provided that the conveying device 100 is arranged between the conveying hose 110 and the gas inlet 26. In particular, it can be provided that the conveying device 100 is part of the mixing unit 20.

The substrate can be a base plate 120, a deposited wax-gas mixture 40 or a base body to be printed. The nozzle 30 is arranged on a positioning system 50, which in the embodiment shown is designed as a robot. In the embodiment shown, the positioning system 50 has a control unit 60, which is designed to control the positioning system 50 for positioning the nozzle 30 relative to the substrate so that a wax formwork is created. The control unit 60 can also be designed as a separate component and connected to the positioning system 50 via a control line or transmitter-receiver devices, which are located both in the control unit 60 and in the positioning system 50 and are connected to each other via radio.

The control unit 60 can be connected to the mixing unit 20, for example via a control line or via transmitter-receiver devices that are arranged both in the control unit 60 and in the mixing unit 20 and are connected to one another via radio. The transmitter-receiver device of the mixing unit 20 can be connected to a sensor (not shown) in the mixing unit 20, which can in particular detect a gas component of the wax-gas mixture in the mixing unit 20 and transmit the sensor data of the sensor to the control unit 60.

The control unit 60 can control the mixing unit 20 depending on the sensor data, so that when gas is mixed into the wax, a wax-gas mixture is formed with a gas proportion that corresponds to a predeterminable target gas proportion. The control unit 60 can be connected to the melting unit 10 and be set up to control the melting unit 10 to heat the wax to a predeterminable temperature above a solidification temperature of the wax.

A cooling and warming device 70 in the form of a hose with an outlet opening through which air flows is arranged on the nozzle. The cooling and warming device 70 serves to cool and/or warm up the deposited wax-gas mixture 40. Depending on whether the deposited wax-gas mixture 40 is to be cooled or warmed up, the cooling and warming device 70 is supplied with cold or hot air.

Figure 2 shows a schematic view of a positioning system 50. The positioning system 50 is again designed as a robot and has a control unit 60. A wax formwork 150 is arranged on a base plate 120. A milling head 130 with a tool drive 140 and a tool for machining 90 in the form of a milling cutter is arranged on the positioning system 50. Instead of a milling cutter, a drill, a reamer or the like can also be used as a tool for machining 90. The tool for machining post-processing 90 is driven by the tool drive 140. The tool drive 140 is connected to the control unit 60 via a control line or transmitter-receiver devices that are arranged in the control unit 60 in the tool drive 140 and are connected to one another via radio. The control unit 60 is designed to detect a machining path for machining post-processing and to control the tool for machining post-processing 90 so that machining post-processing of the wax formwork 150 takes place.

To record the processing path, the control unit 60 can read out a target model of the wax formwork 150, which is also made available to a digital memory (not shown). The target model contains a predetermined model of the wax formwork 150 with all features and dimensions and, if necessary, information about the surface quality of certain surfaces of the wax formwork 150. By machining the wax formwork 150, a deviation of the wax formwork 150 from a target model is reduced and/or a deviating feature of the wax formwork 150 is added and/or changed.

Figure 3 shows a schematic partial sectional view of an embodiment of a mixing unit 20 in a wax formwork manufacturing device. The mixing unit has a mixing chamber 21, which in the embodiment shown is rotationally symmetrical and consists of an upper cylindrical part and a lower conically tapered part. A tempering device 22 is arranged in the upper cylindrical part, which encloses the mixing chamber 21 on its circumference and forms a tempering surface that is part of the outer wall of the mixing chamber 21. The outer wall of the mixing chamber 21 is also the scraping wall. An inlet 24 and a gas inlet 26 are arranged on the top of the mixing chamber 21. The inlet 24 and the gas inlet 26 can alternatively also be arranged on the side of the mixing chamber 21. Wax or already heated wax is fed to the mixing chamber 21 via the inlet 24.

A fan 160 is fluidically connected to the gas inlet 26 and supplies gas to the mixing chamber 21 via the gas inlet 26. As an alternative to a Fan 160 may also be a gas compressor or a pressure vessel containing a compressed gas.

A shaft 27 is arranged centrally in the mixing chamber, which is mounted so that it can rotate about an axis of rotation and is driven by a mixing motor 28. A melting unit 10 with several heating wires is arranged on the shaft 27. The melting unit 10 heats the wax entering the mixing chamber 21 to a predeterminable temperature above a solidification temperature of the wax. A mixing element 29 is arranged on the shaft 27 below the melting unit 10. When the shaft 27 rotates about the axis of rotation, the mixing element 29 mixes the gas into the wax so that a wax-gas mixture is created.

A scraping element 23 is arranged on the shaft below the mixing element 29. When the shaft 27 rotates about the axis of rotation, the scraping element 23 scrapes the wax-gas mixture from the outer wall of the mixing chamber 21. This transports the wax-gas mixture to the outlet nozzle 25. The outlet nozzle 25 is arranged behind the mixing unit 20 in the flow direction and is attached to the mixing unit 20. A valve 170 is on the outlet nozzle 25. The valve 170 can be controllable and in particular can be controlled by the control unit 60.

Figure 4 shows a schematic partial sectional view of another embodiment of a mixing unit 20 in a wax formwork manufacturing device. The mixing unit 20 is designed here as an extruder. The mixing unit 20 has a mixing chamber 21 with a cylindrical part and a conical part. A shaft 27 in the form of an extruder screw is arranged centrally in the mixing chamber 21. The shaft 27 is driven by a mixing motor 28 which is arranged on the shaft 27.

In the flow direction behind the mixing unit 20, an outlet nozzle 25 is arranged, which is attached to the mixing unit 20. On the side opposite the outlet nozzle 25, the mixing unit 20 has an inlet 24 on the top and a gas inlet 26 on the bottom. Alternatively, the inlet 24 can be arranged on the side or bottom and/or the gas inlet 26 can be arranged on the top or side of the mixing unit. Wax or already heated wax is fed to the mixing chamber 21 via the inlet 24. A fan 160 is fluidically connected to the Gas inlet 26 and supplies gas to the mixing chamber 21 via the gas inlet 26. As an alternative to a fan 160, a gas compressor or a pressure vessel with a compressed gas can also be provided, via which gas is supplied to the mixing chamber 21.

On the outside of the cylinder, the mixing unit 20 has two tempering devices 22 in the form of heating bands. The tempering device 22 can also form the melting unit 10 at the same time, so that no separate melting unit is required. The thread pitches of the shaft 27 designed as an extruder screw are the scraping elements 23. When the shaft 27 is rotated by the mixing motor 28, the scraping elements 23 scrape the wax-gas mixture off the outer wall of the mixing chamber 21 and convey it in the direction of the outlet nozzle 25. The outer wall of the mixing chamber 21 is therefore the scraping wall.

List of reference symbols

10 Melting unit

11 Wax inlet

20 Mixing unit

21 Mixing chamber

22 Tempering device

23 Scraping element

24 Entrance

25 Outlet nozzle

26 Gas inlet

27 Wave

28 Mixing motor

29 Mixing element

30 nozzle

40 deposited wax-gas mixture

50 Positioning system

60 Control unit

70 Cooling and warming device

90 Tool for machining

100 Conveyor device

110 Conveyor hose

120 Base plate

130 Milling head

140 Tool drive

150 Wax formwork

160 Fan

170 Valve

Claims

Patent claims

1 . Wax formwork manufacturing device for producing a wax formwork

(150) for concrete casting with

(a) a melting unit (10) for heating the wax to a predeterminable temperature above a solidification temperature of the wax,

(b) a mixing unit (20) designed to mix gas into the wax so that a wax-gas mixture is formed,

(c) a nozzle (30) which is arranged downstream of the mixing unit (20) and is designed to apply the wax-gas mixture layer by layer onto a substrate,

(d) a positioning system (50) for positioning the nozzle (30) relative to the substrate and

(e) a control unit (60) configured to control the positioning system (50) for positioning the nozzle (30) relative to the substrate so that the wax mold (150) is formed.

2. Wax formwork manufacturing device according to claim 1, characterized in that

(a) the melting unit (10) is arranged in the mixing unit (20) or upstream of the mixing unit (20) in the flow direction and

(b) the control unit (60) is arranged to adjust a mass flow of the nozzle (30).

3. Wax formwork manufacturing device according to one of the preceding claims, characterized in that the mixing unit (20)

(a) a mixing chamber (21) with a tempering surface, (b) a tempering device (22) which is arranged to temper the tempering surface to a tempering temperature so that the wax-gas mixture is tempered on the tempering surface of the mixing chamber (21), and

(c) a scraping element (23) for scraping the wax-gas mixture from a scraping wall of the mixing chamber (21) and/or from the tempering surface of the mixing chamber (21). Wax formwork manufacturing device according to one of the preceding claims, characterized by

(a) a cooler arranged to cool already deposited wax-gas mixture (40), and/or

(b) a warming device arranged to warm up already deposited wax-gas mixture (40),

(c) wherein the mixing unit (20) is designed to add a predeterminable gas proportion to the wax. Wax formwork manufacturing device according to claim 4, characterized in that the control unit (60) is designed to automatically carry out a method with the steps:

(a) Determining a target gas proportion,

(b) controlling the mixing unit (20) so that when gas is mixed into the wax, a wax-gas mixture is formed with a gas proportion that corresponds to the desired gas proportion. Wax formwork manufacturing device according to one of the preceding claims, characterized by

(a) at least one tool for machining (90),

(b) wherein the control unit (60) is arranged to

(i) to record a machining path for a machining rework of the wax formwork (150) and

(ii) to control the tool for machining (90) so that machining of the wax formwork (150) takes place. Concrete casting production plant with

(a) a wax formwork manufacturing apparatus according to any one of the preceding claims, and

(b) a concrete feed device for pouring concrete into the wax formwork (150). A method for producing a wax formwork (150) for concrete casting, comprising the steps:

(a) tempering the wax in a melting unit (10) to a target temperature which is above a solidification temperature of the wax,

(b) mixing gas into the wax in a mixing unit (20) to form a wax-gas mixture, and

(c) applying the wax-gas mixture layer by layer to a substrate so that the wax formwork (150) is formed. Method according to claim 8, characterized in that

(a) an application temperature of the wax-gas mixture when applying the wax-gas mixture to the substrate is a maximum of 35 °C, preferably a maximum of 20 °C, particularly preferably a maximum of 10 °C, particularly preferably a maximum of 5 °C, most preferably a maximum of 2 °C below the solidification temperature of the wax and/or a maximum of 10 °C, preferably a maximum of 5 °C, particularly preferably a maximum of 2 °C above the solidification temperature of the wax. Method for producing a concrete component with the steps:

(a) producing a wax formwork (150) using a method according to any one of claims 8 or 9, and

(b) Filling the wax formwork (150) with concrete to create a concrete component.