DESC:FIELD OF THE INVENTION

The invention relates to an additive manufacturing method, an additive manufacturing system, and a non-transitory, computer-readable medium.

BACKGROUND OF THE INVENTION

It is known that large concrete structures, like towers for wind turbines, are assembled from pre-fabricated parts which are assembled on-site. With towers regularly exceeding heights of 100 m, the transport of pre-fabricated parts is increasingly difficult. This is compounded by fact that with increasing height, the diameter and the wall thickness of the concrete structural parts increases as well.

Therefore, methods and systems are required which allow an efficient manufacturing of large concrete structures.

OBJECTIVE OF THE INVENTION

The issues in prior art are addressed by an additive manufacturing method of the present invention using concrete as building material for a concrete structure , wherein a plurality of concrete nozzle devices are performing a movement in a first direction around a closed path, in particular round path and performing a movement in a second direction essentially perpendicular to the movement in the first direction, so that the concrete structure is generated by the concrete exiting from the plurality of nozzle devices under the movements in the first and second direction.

DESCRIPTION OF THE INVENTION

The additive manufacturing method uses concrete as building material for a concrete structure, wherein multiple concrete nozzle devices are used for dispensing or depositing concrete along a prescribed path. The concrete nozzle devices perform a movement in the first direction around a closed path, in particular a round path, i.e. the concrete nozzle devices follow a closed path, in particular a round path, to manufacture a concrete structure with an essentially circular cross-section.

The concrete nozzle devices in addition, perform a movement in a second direction, essentially perpendicular to the movement in the first direction. This movement is a kind of feed movement causing the concrete structure to grow vertically. The concrete structure is therefore generated by the concrete exiting from the plurality of nozzle devices under the movements in the first and second direction.

The two movements of the plurality of concrete nozzle devices in different directions and along different paths allow an effective way to build up the concrete structure. With this combination of movements it is possible to build high concrete structures.

In one embodiment, the axis is perpendicular or vertical to the ground and / or the closed path is perpendicular or vertical to the ground. This allows the efficient building of vertically straight concrete structures by moving the plurality of concrete nozzle devices in a vertical direction while rotating them for the deposition of concrete layers.

In a further embodiment, the movements in the first direction and the second direction take place concurrently or intermittently. The different movements result in a different structure of the concrete layers. If the two movements take place concurrently, the first movement is, strictly speaking, a spiral movement which is essentially considered a circular movement in the horizontal plane. If the movements are coordinated to take place separately, the concrete layers are deposited in circular layers, one layer onto the other.

It is also possible that a further movement of the concrete nozzle devices is superimposed over the movements in the first and second directions, by varying the radial distance of the plurality of nozzle devices from the rotation axis during the movements in the first and second direction and / or in between the movements in the first and second direction. The movement in the radial direction allows the manufacturing of concrete structures with varying diameters, e.g. towers which have wide base and a smaller top. By gradually varying the radial distance, smooth vertical shapes can be generated with this embodiment of the additive manufacturing method.

The concrete gradually hardens after the deposition of the fresh concrete. To stabilize the emerging concrete structure and / or the nozzle devices, one embodiment of the method uses supports, in particular telescopic struts, extending from the axis or the closed path towards the concrete structure, in particular after the concrete of the structure is hardened to some extent. The supports provide some pressure against the just hardened concrete to keep the shape according to specification. The support can, for example, have the form of shells which keep the shape of the concrete structure in shape on the outside and / or on the inside. Generally it can be shaped to prevent or minimize damages to the concrete. In addition or alternatively, a central structure supporting the nozzle devices is axially stabilized by the supports, in particular against vibrations.

In one embodiment, a measurement unit measures the geometric shape and / or orientation of the concrete structure as it is built. Using these measurements, e.g. determining deviations from the correct geometric shape in the cross-section and / or the vertical direction can be detected. Furthermore, it is possible, that a control system adapts the movements of the concrete nozzle devices in the first and / or second directions and / or the concrete flows through the concrete nozzle devices in dependence of the measured data regarding the geometric shape and / or orientation of the concrete structure. If for example a certain skewness in the concrete layering is detected, the concrete flow for the next layer can be adjusted to compensate for the determined skewness. Another possibility is to adjust the supports (e.g. telescopic struts) to achieve a vertical axis. In another embodiment the adaptation can be effected through adjustment of the supports.

The concrete structure does not have to be a homogeneous concrete structure. It is possible that at least one armament application device is moved in coordination with the plurality of concrete nozzle devices to apply at least one armament to the concrete making up the concrete structure. The armament can provide extra strength to the concrete structure. The armament can comprise of fibres, e.g. glass fibres, basalt, textile fibres and / or steel wire or similar reinforcement materials in fiber form or in the form of wires.

There are different ways to apply the armament which also can be used in combination. The armament can for example be applied horizontally in the form of layers, in particular parallel to the application of the concrete and / or the armament can be applied vertically, in particular perpendicular to the application of the concrete. In the first alternative, the armaments are forming layers within the concrete. In the latter alternative, the armaments are oriented perpendicularly to the layer, providing further strengthening of the concrete structure. It is also possible to use armament material as shredded fiber or material which is mixed with the concrete. An example would be fiber-glass pieces with a length of approximately 5 cm which is homogenously mixed with the concrete through extra nozzles. Such concrete can in particular be used on the outer shells of the structure, whereas concrete without armament is used between the shells.

It is also possible, that different concrete compositions are dispensed through at least one of the concrete nozzle devices. This means that for example, concrete with different compositions can be dispensed through one concrete nozzle device at different times. This can also mean that different concrete compositions are dispensed concurrently through different concrete nozzle devices. High-tensile concrete can, for example, be used at the base of a tower, concrete with lesser tensile strength towards the top. Or higher quality concrete is used on surfaces. In particular it is possible that the concrete compositions comprise fibres.

It is possible, e.g. to manufacture the concrete structure as a tower, a chimney or a part of a tower for a wind power generator. Such towers are often completely built with concrete or form hybrid towers which are partly made of concrete, partly made of steel struts.

The issues are also addressed by an additive manufacturing system for building a concrete structure as disclosed in the present invention.

In such a system, a plurality of concrete nozzle devices are movable in the first direction around a closed path, in particular round path and also movable in the second direction essentially perpendicular to the movement in the first direction, so that the concrete structure is generable by the concrete exiting from the plurality of nozzle devices under the movements in the first and second direction. The system is essentially a printing device for a concrete structure.

The plurality of concrete nozzle devices, i.e. the printing heads, are driveably fixed around an axis and / or movable fixed along a closed path, in particular a round path to enable the movement in the first direction, in particular rotating for more than 360° or in an oscillatory movement, i.e. back and forth rotary movement. If there no full rotations, as in the case of the oscillatory movement, the power supply through power lines can be easier to design.

In one embodiment of the system the axis is perpendicular or vertical to the ground and / or the closed path is perpendicular or vertical to the ground. To achieve, the movements, drives (e.g. electric, pneumatic, hydraulic), in particular motors, provide the movements in the first direction and the second direction concurrently or intermittently. Those drives can in particular, be coupled with measurement systems for distance and / or position. The system can also comprise a drive/ device (e.g. electric, pneumatic, hydraulic) for the variation of the radial distance of at least one the concrete nozzle devices from the fixed path during the movements in the first and second direction and / or in between the movements in the first and second direction. With this drive, the diameter of the essentially circular concrete structure can be varied along the vertical axis.

For stabilizing the concrete structure, supports can be used in one embodiment, in particular, telescopic struts, extending from the axis and / or the closed path towards the concrete structure, in particular, after the concrete of the structure is hardened. It is possible that the support structure provides stabilization for a central axis.

It is also possible to include a measurement unit in the system to measure the geometric shape and / or orientation of the concrete structure. In particular the system can comprise of a control system for adapting the movements in the first and / or second direction and / or the concrete flows through the nozzle devices in dependence of the measured data regarding the geometric shape and / or orientation of the concrete structure. It is also possible that the supports are adaptable depending on the measurements of the geometric shape and / or the orientation. With adaptable supports it is possible to shape the concrete and / or stabilize the orientation of the central axis.

For building a composite concrete structure, at least one armament application device is movable in coordination of the plurality of concrete nozzle devices to apply at least one armament to the concrete to the structure. At least one armament can comprise fibres/ fiber materials, in particular glass fibres, basalt, textile fibres and / or steel wire. At least one armament can be applied horizontally in the form of layers, in particular, parallel to the application of the concrete and / or it can be applied vertically, in particular, perpendicular to the application of the concrete.

The concrete structures considered here are typically large, outdoor structures. The system can comprise of a roof structure above the plurality of concrete nozzle devices covering the concrete structure from above and / or from the side to avoid influence from weather like wind, rain or snow.

The data for additively manufacturing the concrete structure can be a computer controlled method or a computer controlled system. Therefore, the issue is also addressed by an non-transitory, computer-readable medium, storing instructions that are operable when executed to cause at least one control unit (e.g. a date processing device) to effect movements of a plurality of concrete nozzle device in the first direction around a closed path, in particular a round path and to effect movements in the second direction essentially perpendicular to the movements in the first direction, so that a concrete structure is generated by concrete exiting from the plurality of nozzle devices under the movements in the first and second direction. It is possible, to use a preprocessing system to predetermine certain movements based on CAD data.

BRIEF DESCRIPTION OF THE INVENTION

Embodiments of the method and the system are shown in connection with the following figures.

Fig. 1 shows a cross sectional side-view through a part of a concrete structure with a system for additive manufacturing positioned within the concrete structure;

Fig. 2 shows a top view of a modification of the embodiment shown in Fig. 1;

Fig. 3 shows a side-view of an embodiment with an armament applicator;

Fig. 4 shows an alternative embodiment with a system for additive manufacturing positioned outside the concrete structure.

DETAILED DESCRIPTION OF THE INVENTION

In Fig. 1 the manufacturing of a concrete structure 10 using an additive manufacturing method and system is shown. The structure shown in Fig. 1 is an example of the bottom section of a concrete tower 10 for a wind turbine generator. In other embodiments, different concrete structures, for example concrete tubings or pipes can be manufactured using an analogue method or device.

The concrete structure 10, being a hollow tube structure with an upwards decreasing inner and outer diameter, is positioned on level ground 11. The concrete structure 10 is in this context, an essentially rotational symmetric structure, with an axis R in the center. The axis R is perpendicular to the ground.

Some deviation from the rotational symmetry is possible, e.g. due to some structures (e.g. ladders, man holes, platforms etc.) which are accessories to the main structure. But overall the concrete structure comprises of a symmetry axis R.

At the center, around the symmetry axis R, a central column 8 is positioned to carry some units of the system for additively manufacturing the concrete structure 10 as will be described below. The central column 8 is also perpendicular / vertical to the level ground.

The additive manufacturing system comprises a plurality of concrete nozzle devices 1, of which only two are shown in Fig. 1. The concrete nozzle devices 1 are mounted at the distal ends of a beam 12 which rotates around the axis R of the central column 8. The nozzle devices 1 performs are moved along a circular round path P. The nozzle devices 1 can be moved in a radial direction on the beam.

The round path P is a special embodiment of closed path P. The path P can, for example, be elliptic, polygonal or have an irregular shape.

As can be seen from Fig. 2, more than two concrete nozzle devices 1 can be used for a faster printing process. The more concrete nozzle devices 1 are used, the faster the printing process. Several concrete nozzle device 1 also allow the use of different concrete types (e.g. for surfaces, inner parts of the concrete structure or especially for parts with high loads).

The concrete nozzle devices 1 are functioning as print head for distributing the concrete in a prescribed shape to gradually build the concrete structure 10 with a circular horizontal cross-section.

For that purpose the concrete nozzle devices 1 are movable in the first direction A around the closed path P, i.e. in this embodiment, a circular path around axis R. In Fig. 1 the double-arrow indicates that the circular movement can be in either direction, in full circles or in an oscillating manner.

This means that movement is essentially planar and perpendicular to the axis R. While rotating once around axis R, one layer of concrete is deposited on the top of a previously laid concrete layer. The width of the layers defines the width of the wall of the concrete structure 10.

In the embodiment shown, the concrete is distributed downwards from the concrete nozzle devices 10. Alternatively or additionally the concrete can also be deposited in a radial direction.

Furthermore, the concrete nozzle devices 1 are movable in a second direction B essentially perpendicular to the movement in the first direction A. This means that the concrete nozzle devices 1 can be moved upwards, i.e. perpendicular to the circular movement in a plane of the first movement A. With this movement upwards, the concrete structure can be built in a vertical direction by adding concrete layer onto concrete layer. Hence by moving the concrete nozzle devices 1 upwards, the concrete structure 10 is generable by the concrete exiting from the plurality of nozzle devices 1.

It should be noted, that the movements in the first direction A and the second direction B can take place concurrently or intermittently. If the movements are made concurrently, the concrete layers can be deposited continuously in form of a spiral. If, for example, the first movement A is completed before the second movement starts, the concrete layers are strictly deposited one after the other.

As indicated in Fig. 1 the concrete structure 10 has smaller horizontal cross sections towards the top. This implies that the radial position of the concrete nozzle devices 1 needs to be adjusted to deposit the concrete in smaller and smaller circles as the movement in the second direction B goes upwards. This can, for example, be achieved by reducing the radial distance D of the plurality of nozzle devices 1 from axis R between the movements in the first and second direction A, B and / or in between the movements in the first and second direction A, B. The movement in the radial distance D can also be continuous for, for example, covering the surface.
If the distance D is increased, the horizontal cross-section becomes larger. In principle, the distance D can be varied to achieve complex profiles for concrete structures, for example, openings for suspension wires.

The embodiment of the system shown in Fig. 1 further comprises supports 2 for the central column 8 once the concrete layers have been deposited.

In the embodiment shown in Fig. 1 the supports 2 are radially extending outwards from the central column 8 (i.e. from the axis R) underneath the concrete nozzle devices 1. Pads at the distal ends of the supports 2 press against the concrete which has already hardened to some extent. The supports 2 can be designed as telescopic struts pressing against the inside of the concrete structure 10. For reasons of simplicity only one strut 2 is shown in Fig. 1. Here three supports 2 are positioned evenly around the axis R, i.e. with a separation angle of 120°.

As the concrete structure 10 is built taller in the vertical direction, more and more supports 2 might be used by applying them to the central column 8. The supports 2 might be located in different heights.

The system for additive manufacturing can further comprise of a measurement unit 3 measuring the geometric shape and / or orientation of the concrete structure 10 as it is built. By using, for example, lasers or cameras, the shape of the diameter in each cross-section can be evaluated with high accuracy. The orientation of the tower and / or the central axis can be checked as well, to determine deviations from the predetermined vertical direction. The support 2 can, for example, be used to adapt the orientation of the central axis. In Fig. 1 the measurement unit 3 is schematically shown at the central column 8 moving upwards with the concrete nozzle devices 1.

With the measurements taken, the building (printing) process can be effectively controlled. A control system 4 adapts the movements in the first and / or second directions A, B and / or the concrete flows through the nozzle devices 1 in dependence of the measured data regarding the geometric shape and / or orientation of the concrete structure 10. It is also possible that the position and the outward directed pressure of the supports 2 can be adapted due to the measurement of the geometric shape and / or the orientation of the concrete structure.

The embodiment of Fig. 1 shows a further feature, i.e. a roof structure 7 positioned vertically above and / or to the side of the plurality of nozzle devices 1. This roof structure 7 protects e.g. the freshly deposited concrete from the effects of weather. The roof structure 7 can move upwards together with the plurality of nozzle devices 1. The side protection can comprise several ring-like elements which can extend in a telescopic way from the top

Fig. 2 shows an alternative embodiment of the system for additively manufacturing a concrete structure 10 in a top view. In principle, the respective description of the embodiment shown in Fig. 1 can be referenced.

As in the embodiment shown in Fig. 1, there is a plurality of concrete nozzles device 1 for deposition concrete layers. For the sake of simplicity only a section of the concrete structure 10 is shown in Fig. 2 with dashed lines. Four concrete nozzle devices 1 are positioned on beams 12 projecting radially outwards from the central column 8. They are rotated by motor (not shown in Fig. 2) in an e.g. counter-clockwise direction (i.e. the first direction A of movement). The angle between the beams 12 is about 30°. In alternative embodiments different angles can be used.

The concrete nozzle devices 1 can be moved in radial direction along the beams 12 as indicated by the double arrows. When the wall of the concrete structure 10 is relatively wide, the concrete nozzle devices 1 can move radially for the deposition of the concrete. The position of the nozzle devices 1 in radial and / or angular position is controlled by the control unit 4 (see Fig. 1).

The embodiment of Fig. 2 furthermore comprises of four armament application devices 5 on a beam 13. The armament application device 5 can also move radially and / or angularly under the control of the control unit 4 (Fig. 1).

The function of the armament application devices 5 is described in connection with Fig. 3 which shows a side view, i.e. radially inwards. The concrete nozzle device 1 is moved in the first direction A to the right as indicated by the arrow. A concrete layer 14 is deposited on previously laid layer 14’, 14’’ of the concrete structure 10.

In the direction of the first movement A in front of the concrete nozzle device 1, is an armament application device 5 which is moved in coordination with the plurality of concrete nozzle devices 1 to apply an armament 6 to the concrete structure 10. The armament 6 can comprise of, for example, glass fibers, basalt, textile fibres and / or steel wire for the enforcement of the concrete structure 10. In Fig. 3 the armaments 6’, 6’’ previously embedded into the previous deposited layers 14’, 14’’ are shown as dashed lines.

The armament 6 in form of a fiber is dispensed from a roll, so that the armament is added to the layer in a horizontal direction, i.e. parallel to the concrete layers 14, 14’, 14’’.

The system shown in Fig. 3 has a further armament application device 5B for the vertical application of vertical armaments 15. The further armament application device 5B can be positioned in front of the nozzle device 1 (as shown) or behind it.

These are short fiber or stick-like parts with a length of, for example, 1 or 2 times the thickness of the concrete layer 14. The vertical armaments 15 are stable against buckling. The application device 5B comprises a dispenser which presses and / or shoots those armaments 15 into the relatively soft concrete 15. Alternatively it is possible that the vertical armaments 15 rolled off a dispenser and cut before the injection into the concrete.

The previous embodiments for the method and the system to manufacture a concrete structure 10 use rotary concrete nozzle devices 1 which were connected to a central column 8, i.e. they were anchored close to the rotary axis R within the concrete structure.

In Fig. 4 an alternative embodiment is described having essentially the same functionality regarding the additive manufacturing. The plurality of concrete nozzle devices 1 (only two are shown in Fig. 4) are performing a movement in a first direction A around the path P which is also a circular path around the axis R, but the driving mechanism, i.e. motors are located outside the concrete structure 10 on a movable scaffold, which can also roll up (and down) the outside of the concrete structure 10. The first movement in direction A is assumed to be clock-wise as indicated in Fig. 4. The movement in the second direction B is essentially perpendicular to the movement in the first direction A, so that the concrete structure is generated by the concrete exiting from the plurality of nozzle devices under the movement in the first and second direction.

Supports 2 for supporting the concrete structure 10 during the additive manufacturing are also mounted on movable scaffold which can move up and down the inner surface of the concrete structure 10. The telescopic arms press against the inside of the concrete structure. The scaffold is only shown schematically in Fig. 4.

The movements of the concrete nozzle device 1 and the supports 2 are under the control of the control unit 4 as described above.

It should be noted, that the embodiment shown in Fig. 4 could be used in conjunction with the other embodiments described. The concrete printing process could be performed from within the concrete structure as well as from the outside.

The embodiments described herein refer to a concrete structure 10 with an essentially circular horizontal cross-section as they are in use for a tower or a part of a tower for a wind power generator. In principle other concrete structures 10 can be additively manufactured.

LIST OF REFERENCE NUMERALS
1 concrete nozzle device
2 support for concrete structure
3 measurement unit
4 control unit
5A armament application device (horizontal application)
5B armament application device (vertical application)
6 armament (horizontal)
7 roof structure
8 central column
10 concrete structure
11 ground
12 beam for concrete nozzles
13 beam for armament application device
14 concrete layer
15 armament (vertical)
A first movement direction of the concrete nozzle device
B second movement direction of the concrete nozzle device
D radial distance
P fixed closed path
R rotation axis
,CLAIMS:We claim:

1. Additive manufacturing method using concrete as building material for a concrete structure (10), wherein a plurality of concrete nozzle devices (1) are performing a movement in a first direction (A) around a closed path, in particular round path (P) and performing a movement in a second direction (B) essentially perpendicular to the movement in the first direction (A), so that the concrete structure (10) is generated by the concrete exiting from the plurality of nozzle devices (1) under the movements in the first and second direction (A, B).

2. Additive manufacturing method according to claim 1, wherein the axis (R) is perpendicular or vertical to the ground (11) and / or the closed path (P) is perpendicular or vertical to the ground (11).

3. Additive manufacturing method according to claims 1 or 2, wherein the movements in the first direction (A) and the second direction (B) take place concurrently or intermittently.

4. Additive manufacturing method according to at least one of the preceding claims, wherein the radial distance (D) of the plurality of nozzle devices (1) from the axis (R) is varied during the movements in the first and second direction (A, B) and / or in between the movements in the first and second direction (A, B).

5. Additive manufacturing method according to at least one of the preceding claims, wherein supports (2), in particular telescopic struts are extended from the axis (R) and / or the closed path (P) towards the concrete structure (10), in particular after the concrete of the structure is hardened.

6. Additive manufacturing method according to at least one of the preceding claims, wherein a measurement unit (3) measures the geometric shape and / or orientation of the concrete structure (10) as it is built.

7. Additive manufacturing method according to claim 6, wherein a control system (4) adapts the movements in the first and / or second directions (A, B) and / or the concrete flows through the concrete nozzle devices (1) in dependence of the measured data regarding the geometric shape and / or orientation of the concrete structure (10).

8. Additive manufacturing method according to claims 6 or 7, wherein the adaptation is effected through adjustment of the supports (2).

9. Additive manufacturing method according to at least one of the preceding claims, wherein at least one armament application device (5) is moved in coordination of the plurality of concrete nozzle devices (1) to apply an armament (6) to the concrete making up the concrete structure (10).

10. Additive manufacturing system for building a concrete structure (10), wherein a plurality of concrete nozzle devices (1) are movable in a first direction (A) around a closed path (P), in particular round path (P) and movable in a second direction (B) essentially perpendicular to the movement in the first direction (A), so that the concrete structure (10) is generable by the concrete exiting from the plurality of nozzle devices (1) under the movement in the first and second direction (A, B).

11. Non-transitory, computer-readable medium storing instructions operable when executed to cause at least one control unit (4) to effect movements of a plurality of concrete nozzle device (1) in a first direction (A) around a closed path (P), in particular a round path (P) and to effect movements in a second direction (B) essentially perpendicular to the movements in the first direction (A), so that a concrete structure (10) is generated by concrete exiting from the plurality of nozzle devices (1) under the movements in the first and second direction (A, B).