NL2017088A

NL2017088A - A structure printing device for printing a three dimensional structure work piece as well as a method for controlling such structure printing device.

Info

Publication number: NL2017088A
Application number: NL2017088A
Authority: NL
Inventors: Hendricus Laarman Joris; Geurtjens Tim; Gilardi Filippo
Original assignee: Mx3D B V
Priority date: 2016-07-01
Filing date: 2016-07-01
Publication date: 2018-01-09
Also published as: NL2017088B1

Abstract

The invention relates to a structure printing device for printing a three dimensional structure work piece as well as a method for controlling such structure printing device. In particular the invention relates to a structure printing device for printing a three dimensional structure work piece, said structure printing device at least comprising: a base; an articulated boom mounted on said base; a printing tool head mounted to said boom; a structure material supply unit for supplying structure material to be printed to said printing tool head; a driving unit for driving at least the boom and the printing tool head in a three dimensional working space; as well as a control print unit for controlling the driving unit, the structure material supply unit and the printing tool head.

Description

A structure printing device for printing a three dimensional structure work piece as well as a method for controlling such structure printing device.

DESCRIPTION

The invention relates to a structure printing device for printing a three dimensional structure work piece as well as a method for controlling such structure printing device.

In particular the invention relates to a structure printing device for printing a three dimensional structure work piece, said structure printing device at least comprising: a base; an articulated boom mounted on said base; a printing tool head mounted to said boom; a structure material supply unit for supplying structure material to be printed to said printing tool head; a driving unit for driving at least the boom and the printing tool head in a three dimensional working space; as well as a control print unit for controlling the driving unit, the structure material supply unit and the printing tool head. A structure print device according to the above preamble is for example disclosed in US2015/059408. Structure print device of the aforementioned kind are also known as three dimensional structure printing device, or simply 3D printers. 3D printers are implemented to construct or print complex three dimensional structures, mainly by means of processing a continuous feed of a plastic material, which plastic material is supplied in the form of a solid thread or fiber or in a stream of powder or pellets to a structure material supply unit, where the plastic is heated and further supplied to the printing tool head in a melted manner, from where melted and softer plastic is ejected and processed at a working position in the working space where the three dimensional structure work piece is being constructed in a layer-for-layer manner.

In another known example of a 3D structure printing device structure material mixed with one or more additives is supplied towards the structure material supply unit, and after ejection the mix of structure material and the additives solidify by means of curing at the working position in the working space. This application for example makes use of concrete as the structure material.

In another embodiment of a 3D structure printing device the structure material is a metal wire, which is fed towards a structure material supply unit, where it is heated to an extent that the printing tool head ‘prints’ a steady stream of molted metal on the three dimensional structure work piece being under construction.

In all applications of constructing a three dimensional structure work piece by means of a 3D structure printing device using a supply of structure material as outlined above the three dimensional structure work piece is constructed or built up in a sequence of layers, which layers are printed on top of each other thus forming the structure work piece.

Hereto the structure work piece is constructed according to a virtual three dimensional representation, for example a CAD/CAM file, from which file the 3D printer is controlled such that the structure work piece is built up in layers of structure material, which layers are deposited on top of each other.

Although with this technique structure work pieces can be constructed in a fast manner a drawback connected to this technique is to be found in that the structure material is being printed in an unstable condition and does require a significant time span to stabilize and solidify, either by curing or by cooling down as the printed layer of structure material serves as the underground support layer for the next layer of structure material to be printed on top of the layer of structure material previously printed.

Also this approach is limited in printing significant overhangs, and when able it always involves a significant amount of support structure to be printed. This significantly increases the printing time, the material usage and adds the necessity of a secondary, time consuming and costly process to remove such supports from the final piece.

This caused stability problems when constructing three dimensional structure work pieces having more complex construction patterns, such as parts that are skewed or inclined relative to the ground surface or parts that hang over a free space. Such stability problems could be overcome by implementing the use of temporarily supportive overhanging constructions, which however have to be removed afterwards requiring additional finishing work.

The structure printing device according to the invention provides a solution for this problem. Hereto said control print unit being arranged in loading a virtual three dimensional representation of the three dimensional structure work piece to be printed; distributing the virtual three dimensional representation into a series of virtual dwell points, each virtual dwell point corresponding with a print dwell position and orientation of the printing tool head in the three dimensional working space; appointing to each virtual dwell point one or more printing parameters; controlling the driving unit, the structure material supply unit and the printing tool head in said three dimensional working space in accordance with each virtual dwell point and the corresponding one or more printing parameters.

By converting the virtual three dimensional representation of the three dimensional structure work piece to be printed in a series or cloud of individual virtual dwell positions and to appoint to each virtual dwell position the specific printing parameters corresponding to the actual print dwell position of the printing tool head in the three dimensional working space and to control the structure printing device sec the printing tool head in each actual print dwell position according to the printing parameters being appointed to that print dwell position an improved 3D structure end piece is obtained in terms of stability, strength and complexity, as well as material optimization (in terms of limited material waste).

In particular three dimension structure work pieces having more complex construction patterns, such as parts that are skewed or inclined relative to the printing direction (either horizontal, vertical or any other orientation imaginable) or parts that hang over a free space can be constructed herewith more easily and with less material use.

Thus a cloud of individual virtual dwell positions is being generated, each virtual dwell position corresponding with a working position of the printing tool head in the working space of the structure work piece being printed and specific printing parameters relative to the deposit of material. The virtual 3D representation of the structure work piece is thus composed of a cloud of points, and the actual 3D structure work piece is being formed point-for-point. The structure printing device according to the invention is thus not controlled in a line or layer like manner, but is controlled in a pointillism manner, wherein the printing tool head is moved towards each actual print dwell position and controlled according to the specific printing parameters appointed to said corresponding virtual print dwell position.

More in particular the one or more printing parameters to be appointed to each virtual dwell point by said the control print unit comprise at least: • a priority level; • the printing procedure to be used by the structure printing device; • the orientation of the virtual dwell point relative to the working space; • a print distance of the printing head tool relative to the actual print dwell position in the three dimensional working space; • a specific amount of structure material to be supplied; • a printing time; • a supply velocity of structure material towards the printing tool head; • a stabilizing (cooling, curing, etc.) time.

Herewith each actual print dwell position is identified and categorized according to the corresponding virtual print dwell position based on which the structure printing device is properly controlled and operated.

In a further aspect the control print unit further comprises at least one sensor for sensing one or more environmental and/or structure parameters near the actual print dwell position within the three dimensional working space and wherein the control print unit is arranged in adapting the one or more printing parameters associated with one or more virtual dwell positions near the actual print dwell position based on the environmental and/or structure parameters being sensed.

This allows for a direct feedback to the control print unit in the event of anomalies, disturbances or simply yet unforeseen or unpredictable changes in the working space and/or on the structure work piece being printed. Furthermore a direct feedback not only senses the occurrence of anomalies but it also keeps track of the whole process in order to be able to foresee eventual problems before they can occur. Any changes are sensed and detected instantly during the printing process and the feedback to the control print unit allows for immediate correction or adaptation of the printing parameters, thus avoiding mistakes in the final end product of the structure work piece.

In particular the one or more sensors comprise at least one temperature sensor, an air humidity sensor, a wind velocity sensor, a surface roughness sensor, a surface contour sensor, a distance sensor and the one or more environmental and/or structure parameters comprise at least: • an ambient temperature; • an ambient air humidity; • an ambient wind velocity; • a local temperature of the structure work piece at or near the actual print dwell position; • a distance; • a local surface roughness or contour of the structure work piece at or near the actual print dwell position.

In yet another aspect of the invention the control print unit further comprises actuating means for affecting one or more environmental and/or structure parameters near the actual print dwell position based on the environmental parameters being sensed. For example, the actuating means comprise a nozzle for directing a cooling agent towards the actual print dwell position, such as a gas. Also the actuating means may comprise a heating element for directing heat towards the actual print dwell position.

This allows also for a direct pro-active cooling or curing or pre-heating of the area near or around the actual print dwell position. Cooling with a cooling agent will effect a direct stabilization of the structure work piece thus avoiding a collapse of the structure work piece. Pre-heating the area near or around the actual print dwell position might also improve the quality and the stability of the structure work piece as the preheated area of the structure work piece will better interact (melt or cure) together with the subsequent added structure material at the actual print dwell position, preventing the occurrence of weak fracture lines or surface cracks in the resulting crystal structure of the structure material being processes.

Pre-heating is also important in case of very large structure print devices where periods of non printing time is involved (for maintenance, breakdown of the structure printing device or so), thus in helping the parts of the structure work piece to be heated to the right temperature before the restart of the printing process. This avoids aesthetic defects in the end result and also helps to preserve the material properties in these critical areas.

In particular the control print unit is arranged in maintaining the printing tool head in a stationary position in each actual print dwell position, thus creating a structure work piece in a dwell point-for-point manner.

The invention also relates to a method for creating a three dimensional structure work piece by controlling a structure printing device, said structure printing device at least comprising: a base; an boom mounted on said base; a printing tool head mounted to said boom; a structure material supply unit for supplying structure material to be printed in a melted state to said printing tool head; a driving unit for driving at least the boom and the printing tool head in a three dimensional working space; as well as a control print unit for controlling the driving unit, the structure material supply unit and the printing tool head.

According to the invention the method comprising the steps of: a) loading a virtual three dimensional representation of the three dimensional structure work piece to be printed into the control print unit; b) distributing the virtual three dimensional representation into a series of virtual dwell points, each virtual dwell point corresponding with a print dwell position of the printing tool head in the three dimensional working space; c) appointing to each virtual dwell point one or more printing parameters; d) controlling the driving unit, the structure material supply unit and the printing tool head in said three dimensional working space in accordance with each virtual dwell point and the corresponding one or more printing parameters.

By converting the virtual three dimensional representation of the three dimensional structure work piece to be printed in a series or cloud of individual virtual dwell positions and to appoint to each virtual dwell position the specific printing parameters corresponding to the actual print dwell position of the printing tool head in the three dimensional working space and to control the structure printing device sec the printing tool head in each actual print dwell position according to the printing parameters being appointed to that print dwell position an improved 3D structure end piece is obtained in terms of stability, strength and complexity.

In particular three dimension structure work pieces having more complex construction patterns, such as parts that are skewed or inclined relative to the ground surface or parts that hang over a free space can be constructed herewith.

With the generation of a cloud of individual virtual dwell positions, each virtual dwell position being considered a point of a zero length. The virtual 3D representation of the structure work piece is thus composed of a cloud of points, and the actual 3D structure work piece is being formed point-for-point. The structure printing device according to the invention is thus not controlled in a line or layer like manner, but is controlled in a pointillism manner, wherein the printing tool head is moved towards each actual print dwell position and controlled according to the specific printing parameters appointed to said corresponding virtual print dwell position.

According to a next aspect of the method step c) comprises the step of appointing one or more printing parameters being selected from at least: • a priority level; • the printing procedure to be used by the structure printing device; • the orientation of the virtual dwell point relative to the working space; • a print distance of the printing head tool relative to the actual print dwell position in the three dimensional working space; • a specific amount of structure material to be deposed; • a printing time; • a supply velocity of structure material towards the printing tool head; • a cooling time.

According to yet another aspect the method further comprises the steps of: e) sensing one or more environmental parameters near the actual print dwell position within the three dimensional working space and f) adapting the one or more printing parameters associated with one or more virtual dwell positions near the actual print dwell position based on the environmental and/or structure parameters being sensed.

This allows for a direct feedback to the control print unit in the event of anomalies, disturbances or simply yet unforeseen or unpredictable changes in the working space and/or on the structure work piece being printed. Any changes are sensed and detected instantly during the printing process and the feedback to the control print unit allows for immediate correction or adaptation of the printing parameters, thus avoiding mistakes in the final end product of the structure work piece.

Furthermore the step e) might comprise the step of sensing appointing one or more printing parameters being selected from at least: • an ambient temperature; • an ambient air humidity; • an ambient wind velocity; • a local temperature of the structure work piece at or near the actual print dwell position; • a local surface roughness or contour of the structure work piece at or near the actual print dwell position.

In another aspect the method further comprises the step of g) affecting one or more environmental parameters near the actual print dwell position based on the environmental parameters being sensed, for example the step of g1) directing a cooling agent towards the actual print dwell position and/or the step of g2) directing heat towards the actual print dwell position.

This allows also for a direct pro-active cooling or pre-heating of the area near or around the actual print dwell position. Cooling with a cooling agent, such as a gas will effect a direct stabilization of the structure work piece thus avoiding a collapse of the structure work piece. Pre-heating the area near or around the actual print dwell position might also improve the quality and the stability of the structure work piece as the preheated area of the structure work piece will better melt together with the subsequent added molten structure material at the actual print dwell position, preventing the occurrence of weak fracture lines or surface in the resulting crystal structure of the structure material being processed.

Other than affecting the one or more environmental parameters near the actual print dwell position based on the environmental parameters being sensed, the device can also modify the printing order or the printing parameters of the dwell points that follows in the generation of the geometry. Points can be skipped, assigned with a different priority level, and in general their set of printing parameters can be changed, where it’s needed.

The invention will now be described in more detail with reference to the accompanying drawings, which drawings show in:

Figure 1a an example of a structure print device operating according to the invention;

Figure 1b a detail of the structure print device of Figure 1a;

Figures 2a-2b examples of the operation of the structure print device according to the method of the invention;

Figures 3a-3d further examples of the operation of the structure print device according to the method of the invention;

Figures 4a-4h aspects of the method of the invention;

Figure 5 another aspect of the method of the invention.

For a better understanding of the invention like parts in the drawings are denoted with like reference numerals.

Figure 1a shows an example of a structure print device 10 according to the invention and which structure print device 10 is operating according to the method of the invention.

Structure print devices 10 are also known as three-dimensional structure printing devices or simply 3D-printers. 3D-printers are implemented to construct or print complex three-dimensional structures, mainly by means of processing continuous feed of plastic material in the form of a solid thread or fibre or in a stream of powder of pallets to a structure material supply unit, from there it is further supplied to a printing tool.

In figure 1a the 3D-printing device 10 at least comprises a base 11 on which an articulated boom 12 is mounted. To the articulated boom 12 a printing tool head 13 is mounted. Also provided is a structure material supply unit 14, which in this embodiment is mounted to the boom 12 and supports the printing tool head 13. In another embodiment the structure material supply unit 14 can be mounted near or at the base 11. In both embodiments the structure material supply unit 14 is provided with suitable supply passageway through which structure material to be printed is to be supplied towards the printing tool head 13.

Reference numeral 15 denotes a driving unit for driving at least the articulated boom 12 and the printing tool head 13 in a three-dimensional working space relative to a working position 17. Furthermore a control print unit 16 is provided for controlling the driving unit 15, the structure material supply unit 14 and the printing tool head 13. The control print unit 16 can be provided with suitable operating instructions, based on which the driving unit 15, the structure material supply unit and the printing tool head 13 as well as the articulated boom 12 are properly operated and manipulated, thus displacing the printing tool head 13 by means of the articulated boom 12 relative to the working position 17 for conducting 3D-printing operations.

The overall 3D-printing device 10 is being driven powered by a separate robot control unit (not shown) in order to properly power, control and position the articulated boom 12 and the printing tool head 13 for transforming, depositing and bonding the structure material at the working position 17.

The printing tool head 13 is also wired to a secondary unit, called welding power source that drives and powers the material melting process. In general, the control print unit 16 communicates the instructions to the robot control unit, the welding power and driving unit and the sensors all together.

As shown in more detail in figure 1b the working position 17 defines a three-dimensional working space through which three-dimensional working space the printing tool head 13 can be displaced at several positions for performing a printing operation.

Reference numeral 20 denotes a three-dimensional structure workpiece positioned at the working position 17 and being printed by means of subsequent print instructions initiated in the control print unit 16 based on which the articulated boom 12, and the printing tool head 13 are manipulated and displaced using the driving unit 15, whereas also structure material supply unit 14 is controlled accordingly for supplying structure material towards the printing tool head 13. The structure printing device 10 as shown in figures 1a and 1b is accorded to the invention operated using specific instructions. In particular and according to the method of the invention, the control print unit 16 is arranged in loading a virtual three-dimensional representation of the three-dimensional structure workpiece 20 to be printed.

The virtual three-dimensional representation of the three-dimensional structure workpiece to be printed is in figure 1a depicted with reference numeral 20’ in the display 16a of the control print unit 16. As shown in figures 4a-4d the virtual three-dimensional representation of the three-dimensional structure workpiece 20 is depicted with reference numeral 20’. The control print unit 16 processes the virtual three-dimensional representation 20’ such that it identifies the outer contour surface lines 21a, 21 b of the actual three-dimensional workpiece 20 to be printed. The outer contour surface lines 21a-21b define the exterior boundary. Within that boundary the printing tool head 13 is to be manipulated and displaced for printing the real three-dimensional structure workpiece 20.

According to the method of the invention the control print unit 16 is furthermore arranged in calculating and generating within the virtual contour boundary 21a-21b of the virtual three-dimensional workpiece 20’ a series or cloud of virtual dwell points 200 (200i...200n, 2011...201 n, 20yi...20yn).

Thus according to the method of the invention the control print unit 16 converts the virtual three-dimensional representation 20’ being defined by the contour surface boundary 21a-21b into a series of virtual dwell points 200i-200n, 2011...201 n, 20yi...20yn wherein each virtual dwell point corresponds with an actual print dwell position of the printing tool head 13 within the three-dimensional working space defined around or near the working position 17.

Furthermore, the control print unit 16 points to each virtual dwell point 200i-200n, 2011...201 n, 20yi...20yn one or more printing parameters bases on which the driving unit 15, the structure supply unit 14, the articulated boom 12 and the printing tool head 13 are operated and positioned within that three-dimensional working space in accordance which each virtual dwell point and the corresponding one or more printing parameters.

Once the printing tool head 13 is positioned at an actual print dwell position within the three-dimensional working space corresponding with a virtual dwell point being generated and identified within the virtual three-dimensional representation 20’ the three-dimensional structure printing device is subsequently operated according to the one or more printing parameters appointed to said virtual dwell point. As shown in figures 2a and 2b the printing tool head 13 and the structure supply unit 14 are positioned in a sequence of print dwell positions 200i...200n, 2011...201 n, 20yi...20yn, which series of print dwell positions form a cloud as defined within the virtual contour boundary of the three-dimensional representation 20’ of the three-dimensional structure work piece 20 to be printed as depicted in figure 4e-4h.

Thus a cloud of individual virtual dwell positions 200 is being generated, wherein each virtual dwell position corresponds with an actual working position (and orientation) of the printing tool head 13 in the working space of the structure workpiece 20 being printed in or around the working position 17. The virtual 3D-representation 20’ of the structure workpiece 20 is thus composed of a cloud of points and the actual structure workpiece 20 is being formed or printed in a point-for-point manner. The structure printing device 10 according to the invention is thus not controlled in a line or layer like manner but is controlled in a pointillism manner wherein the printing tool head 13 is moved towards each actual print dwell position and controlled according to the specific printing parameters appointed to said corresponding virtual print dwell position.

This latter feature of the method and apparatus according to the invention is depicted in more detail in figures 2a-2b. Figures 2a and 2b depict the working position 17 which defines the three-dimensional working space in which the printing tool head 13 can be positioned and orientated using the articulated boom 12 (not depicted in figure 2a-2b). According to the method of the invention the printing tool head 13 is positioned at a sequence of print positions depicted with reference numerals 200i-2003...-200n, 2011...201 n, 20yi...20yn, which form a layer or cloud as being identified in the three-dimensional representation 20’ as depicted in figures 1a-4e-4h.

Each actual print dwell position 200i-200n, 2011...201 n, 20yi...20yn in the working space/working position 17 corresponds with a virtual dwell point of the cloud of individual virtual dwell points being generated and identified by the control print unit 16 as clarified with reference to figure 1a-4e-4h. As one or more printing parameters are appointed to each virtual dwell point being identified in the three-dimensional representation 20’ the printing tool head 13 being positioned at the actual print dwell position corresponding to said virtual dwell position is being operated and controlled according to the specific printing parameters being appointed.

The one or more printing parameters to be appointed to each virtual dwell point and based on which the printing tool head 13 is to be controlled and operated at the corresponding actual print dwell position within the working space 17 comprise at least a priority level, the printing procedure to be used by the structure printing device, the orientation of the virtual dwell point relative to the working space 17, a print distance of the printing tool head 13 relative to the actual print dwell position in the three-dimensional working space 17, a specific amount of structure material to be supplied by the structure material supply unit 14 towards the printing tool head 13, a supply velocity of structure material towards the printing tool head 13 and a stabilising time, for example a time during which the structure material being supplied at the actual print dwell position within the working space 17 is allowed to cool or to be cured.

Each actual print dwell position is identified and categorized within the working space 17 according to the corresponding virtual print dwell position within the virtual representation 20’ based on which the structure printing device 10 is properly controlled and operated. As shown in figures 2a-2b the actual three-dimensional structure workpiece 20 is being build up in a pointillic manner as the printing tool head 13 is positioned towards each actual print dwell position and subsequently operated according to one ore more printing parameters appointed to the corresponding virtual print dwell position, the non-limiting list of printing parameters being described in the previous paragraph.

As shown in figure 2b the three-dimensional structure workpiece 20 is build up point-for-point according to points 200i-200n, 2011...201 n, 20yi...20yn being identified within the virtual surface contour boundary 21a-21b of the virtual three-dimensional representation 20’ as depicted in figures 1a-4e-4h. Please note that herewith a cloud of print dwell positions is generated conforming the geometrical structure of the structure workpiece 20, irrespective of its geometry (having a flat, a curved, or a solid three-dimensional structure geometry).

As the apparatus and method according to the invention are operated in a pointillic manner, thus creating a three-dimensional structure workpiece in a point-for-point manner an improved three-dimensional structure and piece is obtained in terms of stability, strength and complexity. Due the to pointillic build up of the three-dimensional structure workpiece more complex constructional patterns can be emphasized and implemented, such as parts of the three-dimensional structure workpiece that are skewed or inclined relative of the ground surface 17 or parts of the three-dimensional structure workpiece that hang over a free space can be constructed accordingly.

In particular the printing tool head 13 can be operated (that is positioned and orientated) more accurately at each actual print dwell position according to the specific printing parameters appointed to said virtual print dwell point further improving the inner strength and cohesion of the three-dimensional structure workpiece being constructed.

In another aspect of the method according to the invention as depicted in figures 3a-3b the series of virtual print dwell points are not processed in an unbroken sequence as shown in figures 2a-2b, but the printing tool head 13 is operated in a manner wherein one or more virtual print dwell points are skipped as shown in figure 3a. Thus as shown in figure 3a the printing tool head 13 is operated at actual print dwell positions 200i-2003-2005 which actual print dwell positions are spaced apart from each other by a print dwell position (2002-2004-200e-etc.) which are skipped by the control print unit 16 during a first printing run.

The virtual and actual print dwell positions being skipped during the first print run (as depicted in figure 3a) are being processed during a subsequent print run as depicted in figure 3b. Thus herewith the printing tool head 13 is operated accordingly by the control print unit 16 towards the skipped virtual / actual print dwell positions 20O2-20O4-2006-etc, thus depositing an amount of structure material at each skipped actual print dwell position in accordance to one or more printing parameters appointed to said virtual print dwell position.

Skipping one or more actual print dwell positions during a first print run allows the structure material being printed at the actual print dwell positions being processed during the first print run to cool or cure individually for a longer time without being adversely influenced by the structure material being deposited at the directly adjacent actual print dwell position. Thus during the subsequent print run the structure material deposited at the previous processed actual print dwell positions is already cooled down or cured or solidified sufficiently for a longer time before. This is in particular advantageous when structure material is being processed which requires a longer cooling, solidifying or curing time and operating the printing tool head 13 by skipping actual print dwell positions will result in a structure workpiece having an improved inner construction strength and outlook appearance.

According to the method steps of the invention as depicted in 4a-4h the pointillic cloud of virtual print dwell points are being processed one-by-one by the control print unit 16 resulting in the printing tool head 13 being positioned and orientated at each actual print dwell position and operated at said actual print dwell position in accordance with one or more printing parameters listed previously and appointed to each virtual dwell point. As clearly depicted in figures 4a-4h the control print unit 16 will operate the printing tool head 13 according to a specific sequence of virtual dwell points and the structure workpiece 20 is being constructed or built up in a point-for-point manner until the complete cloud of virtual dwell points which form the virtual three-dimensional representation 20’ of the actual three-dimensional structure workpiece 20 are being processed.

In dependence of the geometry of the structure workpiece being built up certain virtual dwell points can be processed at a higher priority level thus constructing or building up the edges of the geometry first, which will act as support ridges or support surfaces already solidified or cured for subsequent actual print dwell positions being processed by the control print unit 16. Herewith structural features of the three-dimensional structure workpiece can be printed in a point-for-point manner, which geometrically are skewed or inclined or overhang a free space.

According to a further aspect of the apparatus according to the invention the control print unit 16 may comprise at least one sensor for sensing one or more environmental and/or structure parameters near the actual print dwell position within the three-dimensional working space 17. These sensors are depicted for example with reference numerals 120-121-122-123 being mounted at the articulated boom 12 near the printing tool head 13. In another embodiment one or more sensors can be positioned at the tip of the printing tool head 13, said additional sensor being denoted with for example reference numerals 130-131.

The sensors 120-123 and/or 130-131 are arranged in sensing one or more environmental and/or structure parameters based on which appropriate control signals are being generated and read out by the control print unit 16 based on which the control print unit 16 may adapt one or more printing parameters associated with one or more virtual dwell positions near the actual print dwell position of the printing tool head 13.

This allows for a direct feedback to the control print unit 16 in the event of anomalies, disturbances or simply yet unforeseen or unpredictable changes in the working space 17 and/or on the structure workpiece 20 being printed. Any of such changes that are sensed and detected instantly during the printing process are returned to the control print unit 16 which feedback of information allows for an immediate correction or adaptation of the printing parameters of subsequent print dwell positions to be printed thus avoiding or correcting mistakes in the final end product of the structure workpiece 20.

For example the one of more sensing means or sensors 120-123 may comprise a temperature sensor, a heat emission sensor, a humidity sensor, a wind velocity sensor, whereas the sensors 130-131 mounted directly at the tip of the printing tool head 13 may comprise a surface roughness sensor, a surface contour sensor of a distance sensor. In particular one of the sensing means 120-123, 130-131 can be implemented as an imaging means or sensor, such as a camera for sensing or imaging the surface of the structure workpiece 20.

With these sensors 120-123, 130-131 environmental and/or structure parameters can be detected such as an ambient temperature, an ambient air humidity, an ambient wind velocity, a local temperature of or heat emission from the structure workpiece at or near the actual print dwell position, a distance between the tip of the printing tool head and the surface of the structure workpiece 20, and a local surface roughness or surface contour of the structure workpiece 20 at or near the actual print well position.

The control print unit 16 can also comprise suitable electronic sensors which provide the control print unit 16 with signals pertaining to the actual operational current and/or operational voltage at which the printing tool head is being operated at a certain print dwell position. The actual operational current and/or operational voltage being sensed are considered being part of the printing parameters defined for said specific print dwell position and feedback towards the control print unit 16 of these operational current and/or operational voltage signals together with the environmental and/or structure parameters obtained with the sensing means 120-123, 130-131 as discussed above allows when necessary for an immediate correction or adaptation of the printing parameters of subsequent print dwell positions to be printed thus avoiding or correcting mistakes in the final end product of the structure workpiece 20.

The structure printing device will also comprise actuating means depicted with reference numerals 140 respectively 141 mounted near the printing tool head 13 and which actuating means 140-141 are controlled by the control print unit 16. The actuating means 140-141 serve to affect one or more environmental and/or structure parameters near the actual print dwell position based on the environmental parameters being sensed with the sensors 120-123 and 130-131.

For example reference numeral 140 may denote a nozzle for directing a cooling agent towards the actual print dwell position. The cooling agent can be for example a gas used to forcibly lower the surface temperature of the structure material being deposited by the printing tool head 13 at the actual printing dwell position thus reducing the cooling time which might improve the quality and the stability of the structure workpiece to be printed.

Reference numeral 141 may denote a heating element for directing heat towards the actual print dwell position which allows for a direct proactive cooling or curing or pre-heating of the area near of around the actual print dwell position.

Cooling by means of the nozzle 140 with the cooling liquid will affect a direct stabilisation of the structure workpiece thus avoiding a collapse of the structure workpiece 20. Pre-heating the area near or around the actual print dwell position using the heating element 141 might improve the quality and stability of the structure workpiece as the pre-heated area of the structure workpiece will better interact (meaning melt or cure together) with the subsequent added or deposited structure material at the actual print dwell position. This will prevent the occurrence of weak fracture lines or surface cracks in the resulting crystal structure of the structure material being processed.

The feedback loop thus created with the sensor 120-123, 130-131 and the actuating means 140-141 is depicted in figure 5. Reference numeral 60 denotes the step of the control print unit 16 loading and processing a virtual three-dimensional representation 20’ of the three-dimensional structure workpiece 20 to be printed distribute in the virtual three-dimensional representation 20’ in a cloud of virtual dwell points as depicted in figure 4a-4h, wherein each virtual dwell point corresponds with a print dwell position of the printing tool head and the printing parameters appointed to each actual printing position. Subsequently during printing/constructing the three-dimensional structure workpiece system feedback is being generated (block 70) by means of information being sensed by the sensors 120-123, 130-131 concerning the environmental and/or structure parameters being sensed and detected during operation of the structure print device which system feedback allows the control print unit 16 to correct or adapt the printing parameters at or near the actual print dwell position making the control print unit 16 and in fact the structure printing device self-learning (block 75). The printing process of the structure printing device as being performed by the control print unit 16 by inputting additional parameters into the control print unit 16 such as measurements of the structure workpiece etc. (block 80-block 85).

It is to be noted that the approach of converting a virtual three-dimensional representation of an actual three-dimensional structure workpiece into a cloud of print dwell points has proven to be the best way to overcome the printing direction limits caused by gravity forces. This printing approach has proven itself as the best way to print an object in any direction, not being constrained to bottom-up approach as in the prior art 3D printing technologies. This technique can print parts horizontally, upside down or following the geometry shape contour flow. So in general this technique aims to offer a way to print not only geometries that presents large overhangs but also geometries that for whatever reason has to be printed in positions different than vertical.

Furthermore printing the three-dimensional structure workpiece in a point-for-point manner allows the material deposited in a liquid state at each print position to solidify for a short time, as in continuous welding the heat keeps the melted material in a liquid state, which results in dripping.

Claims

A construction printing device for printing a three-dimensional construction workpiece, the construction printing device comprising at least: a base; an articulated arm mounted on the base; a printing tool mounted on the arm; a construction material supply unit for supplying the construction material to be printed to the printing tool; a control unit for controlling at least the arm and the printing tool in a three-dimensional workspace; and a control printing unit for controlling the control unit, the construction material supply unit and the printing tool, the control printing unit being arranged in: loading a virtual three-dimensional representation of the three-dimensional construction workpiece to be printed; Dividing the virtual three-dimensional representation into series of virtual work points, each virtual work point corresponding to a print work point of the printing tool in the three-dimensional work space; • assigning one or more print parameters to each virtual work point; • controlling the control unit, the construction material supply unit and the printing tool in the three-dimensional workspace according to each virtual working point and the associated one or more printing parameters.

The construction printing device according to claim 1, wherein the one or more printing parameters assigned to each virtual operating point by the control printer unit comprise at least: a priority level; • the printing procedure to be used by the structural printing device; • the orientation of the virtual work point relative to the work space; • a printing distance of the printing tool relative to the actual printing work position in the three-dimensional workspace; • specific amount of construction material to be administered; • a print time; • a feed rate of the construction material in the direction of the printing tool; • a stabilization (cooling or curing) time.

The construction printing device according to claim 1 or 2, wherein the control printing unit further comprises at least one sensor for measuring one or more environmental and / or construction parameters near the actual printing work position in the three-dimensional work space and wherein the control printing unit is adapted to adjust the one or more print parameters associated with one or more virtual work points near the actual print work position based on the measured environmental and / or construction parameters.

The construction printing device according to claim 3, wherein the one or more sensors comprise at least a temperature sensor, a heat emission sensor, an air humidity sensor, a wind speed sensor, a surface roughness sensor, a surface contour sensor, imaging means or sensors, a distance sensor and wherein the one or more environmental - and / or construction parameters at least include: • an ambient temperature; • a heat emission; • an ambient humidity; • an ambient wind speed; • a local temperature of the construction workpiece at or near the actual printing work position; • a distance; • a local surface roughness or contour of the construction workpiece at or near the actual printing work position.

The construction printing device according to any of claims 3-4, wherein the control printing unit further comprises actuating means for influencing the one or more environmental and / or constructional parameters near the actual printing work position based on the measured environmental and / or constructional parameters.

A construction printing device according to claim 5, wherein the actuating means comprise a nozzle for directing a coolant toward the actual printing work position, such as a gas.

The construction printing device according to claim 5, wherein the energizing means comprise a heating element for directing heat in the direction of the actual printing work position.

The construction printing device according to one or more of the preceding claims, wherein the control printing unit is arranged to maintain the printing tool in a stationary position at any actual printing work position.

A method for creating a three-dimensional workpiece by controlling a structural printing device, the structural printing device comprising at least: a base; an articulated arm mounted on the base; a printing tool mounted on the arm; a construction material supply unit for supplying the construction material to be printed to the printing tool; a control unit for controlling at least the arm and the printing tool in a three-dimensional workspace; and a control printing unit for controlling the control unit, the construction material supply unit and the printing tool, the method comprising the step of: a) loading a virtual three-dimensional representation of the three-dimensional construction workpiece to be printed into the control printing unit; b) dividing the virtual three-dimensional representation into series of virtual working points, each virtual working point corresponding to a print working position of the printing tool in the three-dimensional working space; c) designating one or more print parameters at each virtual operating point; d) controlling the control unit, construction material supply unit and printing tool in the three-dimensional workspace according to each virtual work point and the associated one or more print parameters.

The method of claim 9, wherein step c) comprises the step of designating one or more print parameters selected from at least: a priority level; • the printing procedure to be used by the structural printing device; • the orientation of the virtual work point relative to the work space; • a printing distance of the printing tool relative to the actual printing work position in the three-dimensional workspace; • specific amount of construction material to be administered; • a print time; • a feed rate of the construction material in the direction of the printing tool; • a stabilization (cooling or curing) time.

The method according to claim 9 or 10, further comprising the steps of: e) measuring one or more environmental and / or construction parameters near the actual print work position within the three-dimensional work space and f) adjusting the one or more print parameters at one or more virtual work points near the actual print work position based on the measured environmental and / or construction parameters.

The method of claim 11, wherein step e) comprises the step of designating one or more printing parameters selected from at least: an ambient temperature; • a heat emission; • an ambient humidity; • an ambient wind speed; • a local temperature of the construction workpiece at or near the actual printing work position; • a distance; • a local surface roughness or contour of the construction workpiece at or near the actual printing work position.

A method according to claim 11 or 12, further comprising the step of g) influencing one or more environmental and / or structural parameters near the actual printing work position based on the measured environmental and / or structural parameters.

The method of claim 13, wherein step g) comprises the step of: g1) directing a coolant toward the actual printing work position.

The method of claim 12, wherein step g) comprises the step of: g2) directing heat toward the actual printing work position.