SYSTEM FOR APPLYING A BUILDING MATERIAL

Abstract

A system for applying a building material including: a mixing device for mixing individual components of the building material into a curable building material; a pressure head which can be moved in at least one spatial direction and by means of which the workable building material can be applied; a delivery line, with which the curable building material can be conveyed from the mixing device to the pressure head; at least one delivery device for delivering the curable building material from the mixing device through the delivery line to the pressure head; a feed device, which is designed in such a manner that at least two separate components of the building material can be fed via at least two separate inlets into the mixing device, more particularly into a mixing chamber of the mixing device.

Claims

1. A system for application of a curable building material, the system comprising: a mixing apparatus for mixing individual components of the curable building material to give a curable building material in the setting state; a printing head which is movable in at least one direction in space and by means of which setting building material can be applied; a transport conduit by means of which setting building material can be conveyed from the mixing apparatus to the printing head; at least one transport device for transporting setting building material from the mixing apparatus through the transport conduit to the printing head; a feed device which is configured so that at least two separate components of the curable building material can be introduced via at least two separate inlets into the mixing apparatus.

2. The system according to claim 1, wherein the mixing apparatus is not arranged on the movable printing head and/or no mixing apparatus is arranged on the movable printing head.

3. The system according to claim 1, wherein the mixing apparatus comprises a dynamic mixer and a static mixer.

4. The system according to claim 1, wherein there is an inlet nozzle for admixing an additive to the setting building material in the transport conduit and/or in the region of the printing head.

5. The system according to claim 1, wherein there is an apparatus for aerating and/or deaerating the setting building material.

6. The system according to claim 1, wherein there is an apparatus for changing the temperature of the setting building material.

7. The system according to claim 1, wherein there is a measuring unit for determining a chemical and/or physical property of the setting building material in the mixing apparatus, in the transport conduit, in the printing head and/or after the delivery from the printing head.

8. The system according to claim 7, wherein the measuring unit is designed so that the determination of the chemical and/or physical property can be carried out during application of the building material.

9. The system according to claim 1, wherein an outlet which is controllable in respect of the size of the through-opening is present on the printing head.

10. The system according to claim 1, wherein a control unit is present.

11. The system according to claim 10, wherein the control unit is configured so that the transport power of the transport device is or can be controlled and/or regulated on the basis of a chemical and/or physical property of the curable building material determined using the measuring unit.

12. The system according to claim 10, wherein the control unit is configured so that an addition rate of at least one component of the curable building material by means of the feed device is or can be regulated as a function of the chemical and/or physical property of the curable building material.

13. The system according to claim 1, wherein: a first component of the building material is present in solid form and comprises a mineral binder and optionally aggregates; a second component of the building material is present in liquid form and comprises water; an optional third component comprising a plasticizer is present; an admixture which can be added via the inlet nozzle; where the components and optionally the admixture are present in vessels which are spatially separated from one another and are constituents of the feed device and/or communicate with the latter.

14. The system according to claim 13, wherein the first component comprises a dry mineral binder composition comprising cement and mineral fillers, where the binder composition comprises at least one setting accelerator based on aluminium sulfate, at least one superplasticizer based on a polycarboxylate ether and at least one rheological auxiliary, where the polycarboxylate ether has at least 1 mmol, of carboxylic acid groups per gram of dry polycarboxylate ether.

15. A method for producing three-dimensional objects from curable building materials, comprising printing a three-dimensional object suing the system according claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0224] The figures show:

[0225] FIG. 1 a schematic depiction of an illustrative system for application of a building material;

[0226] FIG. 2 a schematic depiction of an illustrative mixer;

[0227] FIG. 3 a schematic depiction of an illustrative shaft module and drum module of a mixing chamber module;

[0228] FIG. 4 a depiction of a process using a system of the invention.

WORKING EXAMPLES

[0229] FIG. 1 schematically depicts an illustrative system 1 for application of a curable building material. The system 1 comprises a movement device 2 having a movable arm 2.1. At the free end of the arm 2.1, there is a printing head 3 which can be moved in all three directions in space by means of the arm 2.1. In this way, the printing head 3 can be moved to any position in the working range of the movement device 2.

[0230] The printing head 3 has, in its interior, a tubular passage 3.1 for conveying curable building material which runs from the end face facing the arm 2.1 (at the top in FIG. 1) through to the opposite and free end face. At the free end, the passage 3.1 opens into a controllable outlet 4 in the form of a nozzle which can be continuously opened and closed.

[0231] An inlet nozzle 5 for addition of an additive opens laterally into the passage 3.1 in a region facing the arm 2.1. An admixture, for example a rheological auxiliary, can if required, be added by means of the inlet nozzle 5 to the curable building material moving through the passage 3.1.

[0232] Furthermore, a static mixer 6 which additionally mixes the curable building material and the additive while it passes through the passage 3.1 is arranged in the passage 3.1 in the interior of the printing head 3 downstream of the inlet nozzle.

[0233] In addition, a measuring unit 8 for determining the pressure in the tubular passage 3.1 is arranged in the region of the controllable outlet 4. A scanning rate of the measuring unit 8 is, for example, 10 Hz.

[0234] In addition, a device 7 for deaerating the curable building material is installed on the printing head 3. The device is configured as vacuum treatment device and makes it possible to reduce the proportion of air in the curable building material. For this purpose, a section of the wall of the passage 3.1 can, for example, be configured as gas-permeable membrane, so that air is drawn from the curable building material when a subatmospheric pressure is applied outside the passage 3.1.

[0235] This system 1 for application of a curable building material additionally has a feed device 9 which communicates on the inlet side with three vessels 11.1, 11.2, 11.3 and an admixture reservoir 11.4. A component of the curable building material is present in each of the three vessels 11.1, 11.2, 11.3. The first component, which is present in the first vessel 11.1, comprises, for example, of cement and aggregates, by way of example sand and filler. The second component, which is present in the second vessel 11.2, consists, for example, of water. The third component present in the third vessel 11.3 is, for example, a plasticizer in the form of a polycarboxylate ether. In the admixture reservoir 11.4, there is, for example, a rheological auxiliary in the form of modified cellulose and/or a microbial polysaccharide.

[0236] On the outlet side, the feed device 9 has three separate outlets which are connected in each case to one of three inlets 10.1, 10.2, 10.3 of a mixing apparatus 10. The feed device 9 additionally has individually controllable metering devices (not shown in FIG. 1), so that the individual components in the individual vessels 11.1, 11.2, 11.3 can be metered individually into the mixing apparatus 10.

[0237] A further outlet of the feed device is connected to the inlet nozzle 5 (not shown in FIG. 1), so that admixture can be conveyed from the admixture reservoir 11.4 into the inlet nozzle 5 via a further metering device of the feed device 9.

[0238] The mixing apparatus 10 is configured as a dynamic mixer and comprises, apart from this, an integrated transport device in the form of a screw conveyor. In the mixing apparatus, the components which have been individually metered in are mixed with one another and conveyed into the flexible conduit 12 installed on the mixing apparatus on the outlet side. In operation, mixing and transport of the curable building material can be carried out continuously.

[0239] The curable building material can be conveyed through the flexible conduit 12, which opens on the end face of the printing head facing the arm 2.1 into the tubular passage 3.1, into the printing head 3 and be continuously applied through the controllable outlet 4.

[0240] Another constituent of the system 1 is a measuring unit 13 which is integrated into the transport conduit 12 in the region between the mixing apparatus 10 and the printing head 3. The measuring unit comprises, for example, an ultrasonic transducer which is configured for determining the flow properties of the curable material. A scanning rate of the measuring unit 13 is, for example, 10 Hz.

[0241] A central control unit 14 of the system 1 comprises a processor, a memory unit and a plurality of interfaces for receiving data and a plurality of interfaces for controlling individual components of the system 1.

[0242] The mixing apparatus 10 is connected via a first control line 15a to the control unit 14, while the feed device is connected via a second control line 15b to the control unit 14. In this way, the individual components in the vessels 11.1, 11.2, 11.3 can be metered into the mixing apparatus 10 by means of the central control unit according to prescribed formulations stored in the control unit and conveyed at adjustable transport rates into the flexible conduit 12.

[0243] The controllable outlet 4, the inlet nozzle 5 and the device 7 for deaeration of the curable building material at the printing head are each likewise connected via a separate control line 15c, 15d, 15e to the control unit 14 and can be controlled or monitored by the latter.

[0244] The movement device 2 is also connected to the control unit 14 via a further control line 15g. In this way, the movement of the printing head 3 can be controlled by the control unit 14.

[0245] The measuring unit 8 is connected by a data line 15h to the control unit 14 so that printing data measured in the measuring unit can be transmitted to the control unit 14.

[0246] Analogously, the measuring unit 13 is connected by a data line 15f to the control unit 14 so that data which characterize the flow properties and have been measured in the measuring unit can be transmitted to the control unit 14.

[0247] The control unit 14 is, for example, programmed so that: [0248] (i) the addition rates of the three components of the curable building material are controlled by means of the feed device 9 as a function of the flow properties of the curable building material in the flexible conduit determined by means of the measuring unit 13; [0249] (ii) the transport device integrated into the mixing apparatus 10 is controlled as a function of the pressure 8 determined by means of the measuring unit 8 and also the structure of the object to be produced using the curable building material; [0250] (iii) the addition rate of the additive through the inlet nozzle 5 is controlled as a function of the flow properties of the curable building material determined by means of the measuring unit 13 and also the structure of the object to be produced; [0251] (iv) the degree of deaeration of the curable building material in the device 7 is controlled as a function of the flow properties of the curable building material determined by means of the measuring unit 13; [0252] (v) the movement device 2 and thus the position of the printing head 3 is controlled as a function of a model of the object to be produced stored in the data store of the control unit 14.

[0253] The dry mineral binder composition used as first component has, for example, the composition described in Table 1.

TABLE-US-00001 TABLE 1 Composition of the dry binder composition Component % by weight in the binder composition Cement CEM I 52.5 25 Metakaolin 4.5 Betoflow ® D 5 Nekafill ® 15 20 Sand 0-1 mm 42 Denka CSA #20 2 Sika ® ViscoCrete ®-225P 0.25 Carbowet ® 4000 0.5 Modified cellulose 0.05 Inorganic thickener 0.10 Superabsorbent 0.1 Aluminium sulfate 0.5

[0254] The following materials were used here: [0255] Aluminium sulfate is Al.sub.2(SO.sub.4).sub.3.18H.sub.2O, obtainable from Merck, Switzerland. [0256] Betoflow® D is a fine calcium carbonate powder having a particle size of 1-5 μm, obtainable from Omya. [0257] Nekafill® 15 is a ground limestone, obtainable from Kalkfabrik Netstal. [0258] Sika® ViscoCrete®-225P is a pulverulent superplasticizer based on a polycarboxylate ether, obtainable from Sika. [0259] Carbowet® 4000 is an antifoam, obtainable from Air Products Chemicals Europe. [0260] Denka CSA #20 is a shrinkage reducer based on calcium sulfoaluminate cement, obtainable from Newchem, Switzerland.

[0261] FIG. 2 depicts an illustrative embodiment of the mixing apparatus 10 of FIG. 1. The mixing apparatus 10 comprises a drive 20, a drum 21, a proximal closure 22, a distal closure 23, an outlet 24, a first inlet 10.1, a second inlet 10.2, a third inlet 10.3 and a support device 25.

[0262] In this working example, the distal closure 23 is joined via the support device 25 to the drive 20, so that a stirrer shaft (not visible in this image) can be mounted on bearings both in the proximal closure 22 and in the distal closure 23.

[0263] When the mixing apparatus 10 is being used, the first component is, for example, fed in through the first inlet 10.1, the second component is fed in through the second inlet 10.2 and the third component is fed in through the third inlet 10.3.

[0264] FIG. 3 shows the mixing apparatus 10 without the drive module 20 in a disassembled state. In this working example, the mixing apparatus 10 comprises a shaft module 26 and a drum module 27.

[0265] The shaft module 26 comprises a coupling element 28 for mechanical coupling to the drive unit 20, the proximal closure 22, a stirrer shaft 29 and a transport element 30.

[0266] In this working example, the drum module 27 comprises a one-piece tubular drum 31 and also a distal closure 23. The drum 31 has a first inlet 10.1, a second inlet 10.2 and a third inlet, 10.3, which are all arranged in a first end region of the drum 31. The outlet 24 is arranged on a second end region of the drum 31.

[0267] The distal closure 23 has, in this working example, a sacrificial plate 32 which is arranged on one side of the distal closure 23 which faces the drum 31. The sacrificial plate 32 is worn away during operation of the system and can be replaced when required. This enables the distal closure 23 to be used over a longer period of time.

[0268] The transport element 30 is in this working example configured as transport screw. Here, the transport element 30 is arranged such that it can be plugged onto the stirrer shaft 29. In addition, the transport element 30 is secured to the stirrer shaft 29 by a locking element (not visible on this image).

[0269] In the region of the shaft module 26, pins 33 which project radially from the stirrer shaft 29 are additionally attached as stirring elements (only a single pin is shown in FIG. 3).

[0270] FIG. 4 shows a process using the system 1 of the invention. In a first step 41, the dry mineral binder composition from Table 1 (see above) is provided as first component in the vessel 11.1. Water as second component is placed in vessel 11.2 and a plasticizer as third component is placed in vessel 11.3.

[0271] The components are then, in the second step 42, introduced continuously by means of the feed device 9 into the mixing apparatus 10 and mixed with one another there in the next step 43 to give a mineral binder composition mixed with water. The dry binder composition having the composition indicated in Table 1 is mixed in the mixing apparatus 10 with such an amount of water that a weight ratio of water to dry binder composition of about 0.16 is obtained. The plasticizer is metered in in such an amount that a prescribed yield point is achieved. The mineral binder composition which has been mixed with water corresponds to a curable building material in the setting state.

[0272] The binder composition which has been mixed with water is subsequently fed, in the fourth step 44, by means of the screw conveyor integrated into the mixing apparatus 10 via the transport conduit 12 to the printing head 3.

[0273] During feeding to the printing head 3, an admixture in the form of a rheological auxiliary, for example a modified cellulose and/or a microbial polysaccharide, is, in step 45, added in a metered manner via the inlet nozzle 5 to the made-up binder composition as a function of the flow properties of the binder composition determined by means of the measuring unit 13 and/or the binder composition is deaerated by means of the device 7.

[0274] The chemical and/or physical properties are thus adapted when required so that prescribed intended values for the flow properties are adhered to.

[0275] The layerwise application of the binder composition via the outlet 4 of the printing head is subsequently carried out in step 46, so as to produce the object to be made.

[0276] All steps in the process 40 including control of the printing head are controlled and monitored by means of the control unit 14.

[0277] Specifically, a tube having a height of 2 m and a diameter of about 600 mm was produced as example. The individual layers applied had a width of about 30 mm and a height of about 10 mm. The horizontal speed of the printing head was about 40 mm per second. The printing of the shaped body took 2 hours and 40 minutes. The height of the lower layers and of the upper layers differed by not more than 5%. The printed shaped body had a corrugated, very uniform surface without visible defects. Even after storage for 3 days at 25° C. and about 40% relative atmospheric humidity, the shaped body did not display any visible cracks. About 16 hours after application of the last layer, the hollow body was lifted with the aid of carrying straps and a crane onto a transport pallet without damage to the printed shaped body occurring.

[0278] After about 4 days, the shaped body was destroyed by means of a heavy hammer and the fragments were analyzed visually. The fracture surfaces had a uniform surface, without air inclusions or defects. The fracture surfaces did not display any preferential orientation, i.e. the applied layers had equally good bonding between one another as within the same layer.

[0279] The above-described embodiments should be interpreted merely as illustrative examples which can be modified as desired within the scope of the invention.

[0280] Thus, for example, the static mixer 6 can be omitted, so that neither a static mixer nor a dynamic mixer is present in the printing head.

[0281] In addition to or instead of the transport device integrated into the mixing apparatus 10, one or more further transport devices can be provided in the transport conduit 12 and/or in the printing head 3. It is also possible for transport devices other than transport screws to be present.

[0282] It is likewise possible for other measuring units which allow, for example, a temperature measurement to be provided instead of or in addition to the measuring units 8, 13 in the region of the printing head 3 and/or in the transport conduit 12. It is also conceivable for the measuring unit 13 in the transport conduit to be completely omitted or to be integrated in the printing head.

[0283] The mixing apparatus 10 can also have fewer or more inlets, so that additional components which are present in additional vessels can be metered in.

[0284] Instead of one or more of the vessels 11.1, 11.2, 11.3, it is also possible for connections to external sources, e.g. a water connection, to be present.

[0285] It is also possible to program the control unit differently, for example so that a volume flow through the transport conduit 12 and/or the printing head 3 is taken into account.

LIST OF REFERENCE NUMERALS

[0286] 1 System [0287] 2 Movement device [0288] 2.1 Movable arm [0289] 3 Printing head [0290] 3.1 Passage [0291] 4 Controllable outlet [0292] 5 Inlet nozzle [0293] 6 Static mixer [0294] 7 Deaeration device [0295] 8 Pressure measuring unit [0296] 9 Feed device [0297] 10 Mixing apparatus [0298] 10.1 First inlet [0299] 10.2 second inlet [0300] 10.3 Third inlet [0301] 11.1 First vessel [0302] 11.2 Second vessel [0303] 11.3 Third vessel [0304] 11.4 Admixture reservoir [0305] 12 Flexible conduit [0306] 13 Measuring unit with ultrasonic transducer [0307] 14 Control unit [0308] 15a . . . h Control and data powers [0309] 20 Drive [0310] 21 Drum [0311] 22 Proximal closure [0312] 23 Distal closure [0313] 24 Outlet [0314] 25 Support device [0315] 26 Shaft module [0316] 27 Drum module [0317] 28 Coupling element [0318] 29 Stirrer shaft [0319] 30 Transport element [0320] 31 Drum [0321] 32 Sacrificial plate [0322] 33 Pins (stirring elements) [0323] 40 Application process [0324] 41 . . . 46 Process steps