3D OBJECT PRINTING DEVICE WITH AT LEAST TWO PRINT HEADS AND TABLE INTERCONNECTED VIA AT LEAST SEVEN AXES AND METHOD FOR THEIR
FIELD OF THE INVENTION
The invention relates to three-dimensional object moulding where print material is added layer by layer and to three-dimensional object printing / moulding by fused deposition forming (FDM). More specifically, this invention description presents a 3D object printing device with at least two print heads and print table interconnected via at least seven axes. At least two print heads and table are interconnected via at least seven axes and controlled by control systems with artificial intelligence in order to minimize time that object printing takes.
BACKGROUND OF THE INVENTION
The presented invention relates to one of the three-dimensional object printing techniques when the material to make the object being printed is ejected on table in separate layers. Afterwards other layers are placed / cast onto the surfaces that have already been printed and thus the object being printed is moulded layer by layer. In international sources (and sometimes in this description as well) material ejection is called extrusion, and the sprayers ejecting the material are referred to as extruders or print heads. Extruders ensure proper extrusion of the material at the right time. When moulding the print object it is imperative that the print material enters exactly the predefined location: this can be achieved by precise positioning of the print head or table on which the object being printed is being moulded or of the head and the table simultaneously. Materials used for print object moulding are very different, but currently various types of plastics with different additives and characterised by solidifying at specific temperatures prevail.
The start to the era of printers utilizing this print method is seen to have been given by the invention patented by S. Scott Crump in 1989 (US5121329A, 09.06.1992). 3D printers were extremely expensive in those days. Nowadays 3D printers are viewed as one of the most rapidly evolving technologies promising a major change to the world (Richard A. D'aveni. 3-D Printing will Change the World [online] March 201 3 [accessed on 1 7.10.2014] <http://hbr.org/2013/03/3-d-printing-will-change-the-world/>). Mass production of 3D printers and their related proliferation among home users (who can not only purchase but also make them by themselves) resulted from expiration of the said S. Scott Crump patent and substantial decrease of cost of components (precision stepper motors and their controllers).
Regardless of the said proliferation of 3D printers there are still challenges for this technology to be overcome by developers and manufacturers of these devices, and the major of them is increasing the speed of printing without sacrificing the precision of printing an object. This invention description introduces an unseen method to increase speed of printing while ensuring precision of printing an object: the printer has at least two independently moving print heads; table moving on one axis; these objects are linked at seven print axes; artificial intelligence measures are used for controlling these objects, which eventually enable optimisation of head and table movement trajectories and interoperability resulting in efficient increase of speed of operation. Such a printer has no complicated assemblies yet ensures greater speed of operation compared to single-head printers.
Patent application CN103737934A dated 23 April 2014 presents a solution with two sprayers combined in a single print head. This increases speed of moulding the object being printed, however, as both sprayers are built in a single head and cannot move in different trajectories the efficient application of the sprayers to achieve the maximum printing speed is denied.
The source CN203371926U dated 1 January 2014 introduces a 3D printer with two independently moving print heads capable of moving at different speeds. Meanwhile the present invention description presents print heads that not only move in the same way as mentioned in the cited application, but also print speed is further increased and optimised by table moving along Y3 axis. In contrast to the present invention description, the cited application says nothing about the control method.
The source CN203528092U dated 9 April 2014 describes a device where two print heads are moved by one motor utilizing a mounting structure that is triangular in shape. The inventors note that this solution is suitable for moulding multicolour objects without saying anything about possibility to increase speed. The two print heads are intended not for increasing the printing speed, but making it possible to print objects that have more than one colour. The cited application says nothing about table movement and printer control.
The article by TJ McCue dated 28 February 2014 (TJ McCue. 500X Faster - New Ultra-fast 3D Printer In Works [online] 28.02.2014 [accessed on 17.10.2014] <http://www.forbes.com/sites/tjmccue/2014/02/28/500x-faster-new-ultra-fast-3d-printer- in-works/>) gives information about an attempt to make an extremely fast 3D printer. The high speed is achieved, as revealed in the article, by using special form of material (pellets) and much larger than usual diameter of nozzle opening in the print head.
The company "Radiant Fabrication" provides printers with 4 or 8 print heads to increase printing speed. Their solution is based on these quantities of heads. However, all the heads move together, in the same trajectory. (Colin Druce-McFadden. Print your designs faster with this high-speed 3D printer [online] 19.09.2013 [accessed on
f3jjnter>). Meanwhile according to the invention presented in the current description a minimum of two heads are capable of moving independently and in all directions.
The article by Brian Krassenstein dated 16 June 2014 (Brian Krassenstein. 3D Systems Reveals Details of 3D Printing Assembly Line, 50X Faster Than Other Printers [online] 16.06.2014 [accessed on 17.10.2014] <http://3dpnnt.corn/6293/3d-prir¾tirig-asserribiy-Sir e>) gives publicly disclosed information about industrial high-speed 3D printer by "3D Systems" company. The information presented makes it clear that the high speed of operation is achieved by increasing the quantity of print heads and enforcing assembly- line movement of the table on which the being printed object is moulded. This method is different from the invention presented in the current description in that the table presented in the article moves in assembly-line style. Therefore that printer is more for industrial use, which is in contrast to the printer presented in the current description.
SUMMARY OF THE INVENTION
This description presents a 3D printer ensuring higher speed of printing compared to single-head printers, without sacrificing precision of printing and without complicating the printer production and operation.
The main structural feature ensuring the aforementioned characteristics is the use of at least two independently operated print heads and table that are interlinked on at least seven axes (X1 , Y1 , Z1 , X2, Y2, Z2, Y3 etc.). The said axes act as guides of moving components (heads and table) and determine the direction of moving components in the printing space. The movement is enabled by drive mechanism comprising stepper motor, its controller, movement conveying components (threaded rods, pulleys, belts etc.) and other structural units. In case of two print heads and table, axes X1 , Y1 , Z1 are used to change spatial position of one print head, axes X2, Y2, Z2 change the position of another head, and axis Y3 changes the position of table.
To use the characteristics of the said mechanical structure most efficiently for achieving higher speed of printing, artificial intelligence enabling control of entire process of printing is needed. One of the factors that affect printing speed the most is movement trajectories of the moving parts used for printing, specifically print heads and table. Control system of the printer presented in this description is characterised by artificial intelligence measures computing optimal movement trajectories of moving components of printer and their interactions to maximise speed of printing. Artificial intelligence can learn by analyzing the response of the controlled object to control commands and assessing the computed optimal movement trajectories and their possible alternatives. Analysing and learning the control system can adapt to the controlled object in pursuit of the most efficient control: that is, it is characterised by adaptation capability.
The summary of the invention involves at least two print heads and table interconnected via at least seven axes combined with artificial intelligence (characterised by adaptation capability) measures ensuring the highest speed of operation and installed for the purposes of control of the process of printing.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows axonometric projection of 3D printer printing system comprising print heads, table, movement directions and mechanical structures for movement and positioning (view from printer corner).
Fig. 2 shows axonometric projection of mechanical structures for movement and positioning responsible for movement and movement direction of table of 3D printer (view from printer bottom).
Fig. 3 shows system of pulleys and belt, which ensures head movement along Z axis. This system transmits movement from Z axis (connected to Z stepper motor) to axis that is not connected to the stepper motor. Axonometric projection of the drawing, view from top (fragment).
Fig. 4 shows overall axonometric projection of 3D printer view (view from the side). DESCRIPTION OF THE PREFERRED EMBODIMENTS
The embodiment involves two main parts. One of them is the structure including at least two print heads and mechanical structure of the table. Another is control function intended for determining optimal movement trajectory and featuring artificial intelligence with adaptation capability.
For the sake of clarity this description contains description of one print head and all its peripherals only; the structure(s) and functions performed of the other print head(s) is (are) identical. Description of the mechanical part is limited to presentation of components related movement of heads and table. All other components are essentially the same as in other 3D printers that have been on the market for a while.
Print head (1 ) (Fig. 1 ) is fastened via longitudinal-motion bearings to two rods X (2) enabling guiding of print head (1 ) movement along X axis. Print head (1 ) movement along X axis is enforced by X stepper motor (3) the axis of which is rigidly connected to gear pulley (4) (Fig. 2) on which a toothed infinite drive belt (5) with rectangular (or differently shaped) cross-section is put (Fig. 1 ), this belt is rigidly connected to print head (1 ) and put on pulley (6) mounted at the opposite end of X rod (2).
The said X rods (2) are stuck in X fastening members (7) at both ends. The said X fastening members (7) over longitudinal-motion bearings are attached on Y rods (8) that guide their movement in the direction of Y axis. The said Y rods (8) are attached at both ends to Z fastening members (9) that can move in the direction of Z axis only. The said X fastening members are rigidly connected to toothed infinite drive belt (10) with rectangular (or differently shaped) cross-section, which is put at one end on pulley (1 1 ) mounted on Z angular fastening member (9) and at another end on gear pulley (12) mounted on axis (13) mounted over rotary movement bearings in Z angular fastening members (9) and connected to Y stepper motor (14) that creates motion in the direction of Y axis. The said Y stepper motor (14) is mounted on Z angular fastening member (9). Both ends of the said axis (13) have gear pulleys on which toothed belt is put that at the other end is put on Z angular fastening members mounted on pulley. Two belts and four pulleys are necessary for ensuring parallel movement of X fastening members (7) along Y axis.
The said Z angular fastening members (9) are put on Z rods (15) (16) that guide in the direction of Z axis. Movement in the direction of Z axis is ensured by eight (from one side) aforementioned Z rods (1 5) (16) of which four rods (15) have even surface to ensure precise guidance in the direction of Z axis and while the other four are threaded at their entire length: Z threaded rods (16). There is one threaded rod (16) and one plain Z rod (1 5) at each corner. The said Z angular fastening members (9) are fastened to Z rods (15) over longitudinal-motion bearings and to Z threaded rods (1 6) over nut connection that enables conversion of motor axis rotary movement into linear movement in the direction of Z axis. At least one of two Z threaded rods (16) that are at one Y rod (8) is directly and rigidly connected to Z stepper motor (1 7) while another Z rod receives rotary movement over movement transfer system (18) of pulleys and belt that are at the top part of the printer (Fig. 3).
The said Z stepper motor (17) (Fig. 1 ) is attached immovably while the said Z rods (15) and (16) are mounted in base fastening members (19) over bearings (Fig. 2). Rod
(20) parallel to X axis is inserted in the said base fastening members (19) located in the printer corners; to this rod (21 ) parallel to Y axis is fastened, to which table (23) is fastened over fastening members (22) with longitudinal-motion bearings. The said rod
(21 ) parallel to Y axis guides the table (23) to move along Y axis. The said table (23) is rigidly fastened to gear pulley over infinite drive belt with rectangular (or differently shaped) cross-section (24), which at one end of the printer is put on pulley (25) mounted on fastening member (26) connecting rod (20) to rod (21 ) and at the other end of the printer on gear pulley (27) mounted on Y3 stepper motor (28). The said Y3 stepper motor (28) generates table (23) longitudinal motion along Y axis.
The above-described motion-generating mechanical structure can efficiently contribute to increase of speed of operation of 3D printer only if optimal trajectories of movement of print heads and table are ensured. Optimisation of trajectories of movement must take into account presence of all three components (two print heads and table) to ensure optimal trajectories for both movement and interaction of the components.
Artificial intelligence measures are provided for the control system of the 3D printer presented in this description. Artificial intelligence measures are perceived as different mathematical-statistical models (for example, fuzzy logic, artificial neural networks etc) embedded in electronic controls of the device. Electronic controls are perceived as control system hardware part that can be located in the printer itself, in the computer controlling the printer, or both in the printer and the computer. Control system software part is installed in the said electronic implements: in the printer or the computer, or both in the printer and the computer.
To obtain maximum speed of printing the artificial intelligence enabled control of 3D printer optimises movement trajectories and interaction of print heads and table. The result of the optimisation is movement trajectories that require the least time for two print heads and table to print an object; optimisation result can be measured by time it takes to print that object.
Analysing and optimising movement trajectories printer control system must assess actual movement speeds of print heads and table in different directions both when printing and when not printing (as print head only travels from one point to another). The highest speed of printing is obtained with both heads printing at the same time, therefore this is yet another factor to be assessed by the control system in selecting optimal trajectories.
Results of printing of the most commonly printed shapes are stored in a database: it decreases the time that optimisation of subsequent printings takes.
For more thorough analysis of optimisation results, near-optimal trajectories are tested for common forms, optimisation results of these trajectories are compared to actual printing results and reasons are analysed.
In addition to optimisation function, the artificial intelligence enabled control system of 3D printer can continuously learn and improve the methods for obtaining optimal trajectories. To enable learning, feedback collection is provided, which makes it possible to track actual print times. Tracking actual print times and comparing them with optimisation results allows identification of possible causes of mismatches, which are assessed and used for subsequent optimisations.
Learning function is a precondition for adaptation capability. Control system compares trajectory optimisation results with actual print results, analyses causes of possible mismatches, and depending on these causes modifies optimisation algorithm, i.e. it adapts to peculiarities of the object controlled. Occurrence of particularly big mismatches may be a symptom of malfunctioning (wear) of mechanical part - therefore, the control system with artificial intelligence can identify certain malfunctions and do their prevention.
3D printer control delivers increased speed of operation: two print heads combined with moving table prints a given object faster compared to separately operating print heads with no common control.
As mentioned before, figures illustrating the structure along with their explanations are given only insofar as necessary for disclosure of the essence of the invention. Fig. 4 shows 3D printer with enclosure (30) and devices (31 ) from which printing material in unwound. The term "rod" used here allows for more accurate description of components of 3D printer. Elsewhere in this description a broader and more general notion "axis" is usually used that coincides with the term "rod" in certain cases. The term "axis" denotes both a structural component of printer and a direction in coordinate system.
Position points denoting terminal points of print head delimit the space that can be called a print head working area. Print head working area is spatial position where print head can be.
To illustrate and describe this invention, description of preferred embodiment is given above. This is not a complete or limiting description aimed at prescribing a precise embodiment or implementation option. The description given above should be regarded more as an illustration than a constraint. Obviously, the specialists in this field may clearly see a multitude of modifications and variations. The embodiment has been selected and described so as to enable the specialists in this field to best understand the principles behind this invention and their best practical application for different embodiments with different modifications fit for a specific application or embodiment customisation. The invention scope is defined by the attached claims and their equivalents wherein all the used terms have the broadest possible meanings unless stated otherwise.
Embodiments described by specialists in the respective field may contain changes that do not depart from the scope of this invention, as described in the claims given next.