Patent Application
20220055249
The invention concerns the technique for the reinforcing of structures that are made with the use of concrete, especially devices for automatic reinforcement, as well as the method for the reinforcing of structures, especially with the use of the device according to the invention.
In the construction industry, reinforcement of concrete structures is required because the tensile strength of concrete is many times lower compared to its compressive strength. In bending elements, such as ceilings or lintels, there occurs both compression and tension, which enforces the use of reinforcement. In connection with the progressing automation of the process of erection of buildings and constructions, there is also an economically justified need to automate the process for the laying of reinforcement.
In the prior art, various types of devices can be found which try to provide automation of work when laying reinforcement fibres. For example, the American application US2018093373 A1 describes a comprehensive device for automatic execution of buildings and constructions. It consists of a large-sized 3D printer, which is adapted to the controlled pouring of concrete layers. According to this document, reinforcements are laid using a multi-axis, multi-purpose manipulator, which is able to place metal bars in the produced structure and even weld them together. However, the proposed method for reinforcement with the use of the described device is difficult to implement, because the device according to this invention is large, very expensive, and (though it can be suitable for the erecting of large constructions, such as power plants) it is not suitable for smaller-scale applications, such as residential houses.
Document WO0151730 A1 proposes a new type of reinforcement bars made of fibres immersed in resin and formed into various shapes. However, this document provides for the laying of bars made of new materials that are similar to the laying of well-known metal bars, i.e. creating of a (spatial) reinforcement structure and pouring of concrete over it. This is disadvantageous in that it requires human intervention to produce the spatial reinforcement, due to which it does not allow full automation of the process of creating a reinforced building.
Document WO2014153535 A2 describes incremental creation of structures using fibres which, after being combined with thermoplastic resin, can be used to create 3D structures. However, the document does not consider the use of such fibres with a resin matrix to reinforce concrete structures at all, and describes the use of thermosetting resins without considering the benefits of using chemosetting resins.
Application US2017028644 A1 describes a method for in situ creation of two-component composites for the purposes of creating lightweight structures (aircraft parts, wind turbine blades). However, it does not consider the use of the produced composite in connection with concrete, and a composite that only has two components is far from sufficient when it comes to being able to ensure adequate strength parameters and bonding of reinforcement to concrete.
Publication entitled “Experimental Exploration of Metal Cable as Reinforcement in 3D Printed Concrete” by Freek P. Bos, Zeeshan Y. Ahmed, Evgeniy R. Jutinov, Theo A. M. Salet, Materials, 2017, which constitutes the closest prior art relative to this invention, describes attempts to incrementally produce concrete structures in which the reinforcement fibre would be laid together with the concrete filament—in the centre of the filament. Unfortunately, such a solution is not suitable due to the problem with the proper laying of reinforcement—very thin fibres turn out to be too weak, thicker fibres tend to slip out of the concrete filament, and every type of fibre has a tendency to straighten up, which limits the creatable shapes of the concrete structures reinforced in this way. Moreover, the placing of the fibre inside the concrete filament makes it difficult to bind the reinforcement fibres together, thus reducing the achievable strength of the entire reinforced structure.
In view of the above, it is evident that the prior art lacks devices that would enable quick and cheap in situ production of composite reinforcements for concrete structures using relatively small-sized equipment, and that there are no described methods for achieving such reinforcement.
The object of the invention is the device for automatic reinforcement of structures, especially concrete structures, which comprises:
Preferably, there are guide rollers placed between the reinforcement fibre storage unit and the drive rollers, which guide rollers preferably have rotation axes perpendicular to the rotation axes of the drive rollers.
Preferably, the device has a saturator positioned so that the reinforcement fibre first passes next to the cutting knife and then through the saturator, as well as two containers—with resin and hardener—connected to a hardener mixing chamber and pumps assembly, and the outlet of the hardener mixing chamber is directed towards the saturator.
Preferably, the device has a glue tank, a glue pump, and a nozzle of the gluing assembly, where the nozzle of the gluing assembly preferably faces the same direction as the outlet of the saturator.
Preferably, on the endpiece of the manipulator there is a nozzle that deposits the concrete mortar.
Preferably, the device has the means for cleaning the hardener mixing chamber and pumps assembly and/or the nozzle of the gluing assembly, preferably blowing through or flushing out.
Preferably, the device has a light-emitting module, which is preferably directed towards the outlet of the reinforcement fibre from the saturator.
Preferably, the device has an assembly that sprinkles—with aggregate—the reinforcement being laid, preferably including a vibratory conveyor.
Preferably, the nozzle that deposits the concrete mortar is placed at a distance from the means for laying the fibre on the surface of the structure being reinforced, and this nozzle is configured so that the point of exit of the reinforcement fibre from the means for laying the fibre on the surface of the structure being reinforced is entirely outside the outlet of the nozzle that deposits the concrete mortar.
The object of the invention is also the method for automatic reinforcement of structures characterized in that the fact that with the use of a remote-controlled device the following steps are carried out:
a) a bundle of the reinforcement fibre is lowered until it comes into contact with the surface of the element being reinforced;
b) the bundle of the reinforcement fibre (in particular—its end) is attached to the surface of the element being reinforced, by applying a small amount of glue, preferably quick-setting glue;
c) the bundle of the reinforcement fibre is embraced by the saturator;
d) the supply of the hardening mixture to the saturator begins;
e) the printhead is moved, placing the saturated reinforcement fibre on the surface being reinforced;
f) the reinforcement fibre is cut.
Preferably, the method according to the invention for automatic reinforcement of structures is implemented using the device according to the invention, characterized in that the following steps are performed using the remote-controlled device:
a) a bundle of the reinforcement fibre, unwound from the storage unit, is lowered until it comes into contact with the surface of the element being reinforced;
b) the bundle of the reinforcement fibre (in particular—its end) is attached to the surface of the element being reinforced, by applying—using the nozzle of the gluing assembly—a small amount of glue, preferably quick-setting glue;
c) the bundle of the reinforcement fibre is embraced by the saturator;
d) the supply of the hardening mixture from the containers with resin and hardener to the saturator begins, using the hardener mixing chamber and pumps assembly;
e) the printhead—mounted on the endpiece of the manipulator—is moved, placing the saturated reinforcement fibre on the surface being reinforced;
f) the reinforcement fibre is cut by the cutting knife.
Preferably, after the reinforcement fibre is cut according to step f), the following step is carried out
g) the end of the reinforcement fibre is covered in glue, especially glue deposited through the nozzle (9).
Preferably, when laying the saturated reinforcement fibre according to step e), the resin-coated reinforcement fibre—which is being laid on the surface of the element being reinforced—is sprinkled with aggregate.
Preferably, the resin is formed into irregular shapes, locally oversaturating the reinforcement fibres.
Preferably, in the case of using photocurable resins, during step e) and/or after cutting off the reinforcement fibre according to step f), the laid reinforcement fibre is exposed to light, especially UV light.
Preferably, before beginning to reinforce the surface of the element, projections are created on this surface, especially by previously forming these projections from concrete and/or putting pegs in this surface, especially made of metal, plastic, concrete, or aerated concrete,
wherein, during step e), the reinforcement fibre is laid on the surface being reinforced around at least some of the projections.
Preferably—after steps a) to f) and possibly g) have been carried out one time or many times, and after the first layer of reinforcement has been created on the surface of the concrete base—auxiliary posts are created,
after which steps a) to f) and possibly g) of the method are carried out again, during which a second layer of reinforcement is laid, whose reinforcement fibres run both on the surface of the concrete base and on the surface of the auxiliary posts, wherein, additionally, glue joints are created between the reinforcement fibres of the first layer of reinforcement and the reinforcement fibres of the second layer of reinforcement.
Preferably, after laying the second layer of reinforcement, steps a) to f) and possibly g) of the method are carried out again, during which a third layer of reinforcement is laid on top of the auxiliary posts, wherein glue joints are created at the places where the reinforcement fibres of the second layer of reinforcement and the third layer of reinforcement meet.
Preferably, after the second layer of reinforcement has been laid, a layer of concrete is poured over the surface being reinforced up to the level of the top of the auxiliary posts.
The invention shall be described in more detail in relation to the enclosed drawing in which:
Most importantly, the device for automatic reinforcement of structures has a printhead, which is presented in an example configuration in
Among the elements of the printhead that are presented in
Next to the reinforcement fibre storage unit (2) there are the guide rollers (3), which can take the form of cylinders that are preferably narrowed in the middle so that—as the fibre is unwound from the storage unit (2)—the reinforcement fibre can pass stably between the guide rollers (3) without sliding out beyond the guide rollers (3).
Next to the guide rollers (3) (in
The cutting knife (5), which can be seen in
Next to the cutting knife (5) there is the saturator (6), where the reinforcement fibre comes into contact with the substance that saturates the reinforcement fibre, especially resin. The saturator (6) can be any prior art saturator designed for the saturating of glass or carbon roving, or it can be a structure that uses the gravity force—in such a case, it takes the form of a funnel divided into two or more parts preferably made of elastic material, e.g. rubber or silicone rubber. The reinforcement fibre—under the influence of the drive rollers (4)—is pressed through the saturator (6), thanks to which the surface of the reinforcement fibre gets covered in resin, while any excess resin is collected from the fibre at the narrowed part of the saturator (6).
The saturator (6) is located near the outlet of the hardener mixing chamber, which constitutes a part of the hardener mixing chamber and pumps assembly (8) presented in
The reinforcement fibre, after passing through the saturator (6), is already covered with the hardening mixture and is near the surface on which it is supposed to be laid. After coming into contact with the surface, it adheres to it and forms the reinforcement bar (11) marked in
The device presented in
Alternatively, thermoplastic can be used instead of glue. The head will then consist of a heated nozzle, a container with the plastic in the form of pellets or a reel of wire, and a drive that presses the wire into the heated nozzle.
An additional element of the printhead of the device according to the invention may be the nozzle that deposits the concrete mortar (12). Its integration with the head that deposits the reinforcement may ensure full automation of the erection of reinforced concrete structures using a single device—in such a case, the stages of depositing a layer of concrete and creating the reinforcement happen in an alternate fashion. What is more, due to the need to ensure high precision of the manipulator—on whose endpiece (1) the head for depositing the reinforcement is located—integration of the nozzle (12) with the head that deposits the reinforcement may ensure greater accuracy of the process of depositing sub-sequent concrete layers.
It is obvious that—due to the great freedom of configuration of the printhead's shape as well as of selection of materials (reinforcement fibres, glue, hardener)—many simple modifications of the head of the device according to the invention are possible. For example, if photocurable resins were used, then it would be preferable to place a light-emitting module (e.g. a UV LED) on the head, at a place that would allow effective illumination directed towards the reinforcement being laid.
Optionally, if the fibres being laid are saturated with thermoplastic, the head may have an additional nozzle that blows-in compressed air in order to cool down the reinforcement being laid. It may be preferable to use compressed air at an additionally reduced temperature, e.g. by applying a vortex tube.
Another optional solution—in the case where the fibres are saturated with a thermosetting binder—they can be hardened by being heated with an infrared radiator, a visible light radiator, a microwave radiator, hot air supply, or by means of electromagnetic ex-citation of eddy currents for fibres that conduct electric current.
In order to control the temperature for both thermosetting, thermoplastic binders and chemosetting binders (in whose case the correctness and duration of the hardening process depend on the temperature), the heating or cooling process can be carried out while being feedbacked with a thermal imaging camera or a contactless temperature sensor.
In turn, when it comes to selection of the most suitable ingredients for various applications, it may transpire to be preferable to use appropriate additives that reduce the flammability of the plastic contained in the reinforcement bar (11), e.g. melamine derivatives, ammonium polyphosphate, aluminium hydroxide (typically mixed in a ratio of 1:1 with epoxy resin), tetrabromobisphenol A (for epoxy resins), antimony(III) oxide.
Moreover, even though reinforcement fibre mixed with a hardener has been described and presented in
Another preferable additional module of the head of the device according to the invention is an assembly that sprinkles the fibre being laid with aggregate, e.g. glass aggregate or another granular material. The sprinkling with aggregate of the fibre being laid that has not been hardened yet increases its later adherence to the concrete with which the fibre is supposed to be covered later. The assembly that sprinkles with aggregate can preferably take the form of vibratory conveyors well known in prior art, activated at the right time—especially after a bundle of reinforcement has been laid and after the fibre has been cut off by the cutting knife (5). However, it is necessary that the aggregate be deposited on the reinforcement fibre before the fibre hardens, so that it can adhere to its surface.
Additional preferable elements of the device according to the invention that have not been presented in
The process of cleaning the elements of the head (by both blowing them through and flushing them out with a solvent) preferably happens outside the place where the reinforcement is being created (when the manipulator moves the head out of the working area), e.g. so that drops of the solvent do not weaken the already created reinforcement.
Thanks to the fact that the bars are laid in unhardened form, the adhesion between the base and the reinforcement bar is increased compared to traditional solutions, and, additionally, freedom of the reinforcement's shape is achieved, which allows to use less material while keeping the same strength parameters.
Since the material, which plays the role of the binder, can still be in liquid form during the laying of the reinforcement bar, the bar becomes glued to the other bars that were laid earlier and now intersect it. This solution eliminates the need to bind the fibres of the reinforcement, which is very time-consuming in the case of traditional reinforcements.
The process of laying the reinforcement—using the device according to the invention—starts with lowering a bundle of reinforcement fibre until it comes into contact with the element being reinforced, using drive rollers (4), and then attaching the bundle using a small amount of quick-setting glue deposited with the nozzle (9).
Once the bundle of the fibre has been attached to the element being reinforced, the fibre is embraced by the saturator (6) and the head is moved by the manipulator thus laying the bundle of the saturated fibre on the surface of the element being reinforced.
When the laying of the bundle of the fibre has been completed, the fibre is cut by the cutting knife (5) and then the end of the laid fibre can additionally be covered with glue from the nozzle (9).
After the reinforcement has been laid, it is poured over with concrete, or covered with concrete by means of the nozzle of a device that builds using an incremental technique.
In order to increase the adhesion of the reinforcement to the concrete mix, it is possible to apply a sprinkling of the still-liquid saturant with aggregate, or to form the resin into irregular shapes by locally oversaturating the fibres.
Another known method is to braid the main bundle of the reinforcement with an additional fibre—the achieved helix on the surface of the fibre increases its adhesion to the concrete mix. The use of such an additionally braided reinforcement fibre would make it necessary to expand the device, at least by adding an additional reel for the braiding bundle, guiding means, and a socket in which the braiding bundle would come into contact with the reinforcement fibre—such a modification is possible, and, for an expert, it would not be difficult to select appropriate elements from among the already-known devices, guides, etc.
Application of the device in combination with incremental-building techniques also allows to create the auxiliary structure that can be seen in
Directional changes in the reinforcement, and tensioning of the fibre can be ensured by means of pegs placed in the structure. The pegs can be placed by means of a dedicated head and can be made of, e.g., metal, plastic, concrete, or aerated concrete. They can also be made in situ by a machine, e.g. from a concrete mix, or from foams.
In the case of pre-tensioning of the fibre, it may be necessary to use a saturator of increased strength (because, in this case, this is the last element from which the fibre gets out onto the surface being reinforced, so it would also be the element bearing the most load) or to use an additional element such as a fixed ring that would tension the fibre during the creation of pre-tensioned patterns of the reinforcement.
It is also possible to achieve a spatial structure of the reinforcement by making the concrete superstructures depicted in
In the presented example, the possibilities for the precise creation of concrete structures with incremental techniques and for the free laying of reinforcement with the device according to the invention are fully taken advantage of. First of all, on the previously produced concrete base (30), the first (usually flat) layer of reinforcement fibres is laid, thus forming the first layer of the reinforcement (33). Then, e.g. using the nozzle (12), auxiliary posts (31) are created, thus covering a part of the first layer of the reinforcement (33). Once the auxiliary posts (31) are sufficiently dry/hardened, the second layer of reinforcement is laid (35), which is now a spatial structure—the fibres of this layer are laid on the concrete base (30) where (at least in some places) they are glued with the first layer of the reinforcement (33), and at the places where there are auxiliary posts (31) the fibres of layer 35 are laid on their surface (running up on the walls, passing on their surface, coming down on the other side again towards the base (30)). Optionally, at the intersections, they can be additionally bonded with each other, e.g. by means of glue joints (34). After the second layer of the reinforcement has been created (35), the base (30) together with the posts (31) is poured over with the next layer of concrete that reaches approximately the upper end of the posts (31) (so that at least a part of the second layer of the reinforcement (35) protrudes above the level of the filling (32)). At this stage, it is possible to lay the third layer of the reinforcement (36), attached to the second layer of the reinforcement (35) by joints (34) at the points of contact with the second layer of the reinforcement. In this way, a structure of reinforcement is achieved in which the lower layer of the reinforcement (the first one—33) is permanently connected to the upper layer of the reinforcement (36) through an intermediate layer of the reinforcement (the second one—35) using the joins (34).
There are many other possible ways of creating three-dimensional reinforcement structures—e.g. by changing the order of the scheme described above, and first creating the third layer of the reinforcement (36) before the filling (32) is poured. In this way of proceeding, the fibres of the third layer of the reinforcement (36) should first be attached (for example) to one of the posts (31), and then they should be run—in the tensioned state—all the way to the next post (31), where they would be bonded to the fibres (that already exist there) by means of the joint (34), and so on. Preferably, the maximum distance between the consecutive posts (31) on which the reinforcement fibre would be supposed to be suspended is less than 1 m.
Preferable materials for the laying of reinforcements using the device according to the invention are glass, carbon, basalt, aramid, diolen, or other fibres, which can then be saturated with a chemosetting saturant mixture, thermoplastic, photocurable plastic, or thermosetting plastic.
The device according to the invention has been designed, among other things, to be used as a component of systems for the automatic erection of constructions using additive techniques.
| Number | Date | Country | Kind |
|---|---|---|---|
| P.427016 | Sep 2018 | PL | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2019/069290 | 7/17/2019 | WO | 00 |
