WO2020071933A1

WO2020071933A1 - 3d printer and a method of operating the same

Info

Publication number: WO2020071933A1
Application number: PCT/RO2018/000017
Authority: WO
Inventors: Eric Gengoux; Stephane TAMPIGNY
Original assignee: 3 Digital Edge Srl
Priority date: 2018-10-02
Filing date: 2018-10-02
Publication date: 2020-04-09

Abstract

A 3D printer (1) comprises a printing base (2), a central support (3), rotating about a vertical axis, at least one arm (4) coupled to the central support (3) in a translational manner and rotating with the central support (3) about the vertical axis over a working area, a printing tool support (5) connected to the arm (4) in a translational manner, a printing tool (6) spreading a build material (8) via a printing head (7) over the working area, wherein the build material (8) is to be formed layer-by-layer into a 3D object and wherein spreading of build material (8) is done following a predetermined trajectory which combines the linear and angular movements of the arm (4) and printing tool support (5) with the movement of the central support (3). A method of operating said 3D printer (1), to form a 3D object is described.

Description

3D PRINTER AND A METHOD OF OPERATING THE SAME

Description

Field of the invention

[0001] The present invention relates to a 3D (three-dimensional) printer for efficient 3D printing 3D objects on a fixed surface from a wide variety of media adequate to be used with 3D printing technologies, such as polymeric, resin, organic or metallic materials and to a method of operating the same.

Background of the invention

[0002] 3D printing is a form of additive manufacturing (AM) technology where a 3D object is created by laying down successive layers of material. It is also known as Additive manufacturing (AM). 3D printing is achieved using an additive process, where successive layers of material are laid down in different shapes.

[0003] In recent years, 3D printing has been demonstrated to be an effective technique for accurately forming 3D objects, such as for the purpose of rapid prototyping, architectural scale models, maquettes and manufacture. Other examples of 3D printing would include reconstructing fossils in paleontology, replicating ancient artifacts in archaeology, reconstructing bones and body parts in forensic pathology, prosthetics, movie props, confectionery products and so on.

[0004] In its more general sense, 3D printing typically utilizes a 3D scanner and/or computer software (e.g. a computer aided design (CAD) package) to generate an image map of a desired object. That image map is then translated into a grid-like structure such that a fabrication device can deposit on a working area a flowable adequate build/printing material such as a polymer, resin or organic material via an additive process which is simultaneously solidified creating a 3D object.

[0005] Fused deposition modeling (FDM) or Fused Filament Fabrication (FFF) 3D printers are the most used 3D printers as of 2018 with Selective Laser Sintering (SLS) 3D printers coming in second.

[0006] FDM (FFF) is a method of rapid prototyping commonly used for modeling, prototyping and production applications. FDM (FFF) is also known as a solid-based AM technology. The FDM (FFF) technology works using a plastic filament or metal wire which is unwound from a coil and supplying material to an extrusion nozzle which can turn the flow on and off. The nozzle is heated to melt the material and can be moved in both horizontal and vertical directions by a numerically controlled mechanism, directly controlled by a computer-aided manufacturing (CAM) software package. The nozzle follows a tool trajectory controlled by a computer-aided manufacturing (CAM) software package and the piece is built from the bottom up, one layer at a time. Stepper motors or servo motors are typically employed to move the extrusion head. The mechanism used is often an X-Y-Z rectilinear design, although other mechanical designs such as deltabot have been employed. The technique fuses parts of the layer and then moves the working area downwards, adding another layer of material and repeating the process until the 3D piece has build up. This process uses the unfused media to support overhangs and thin walls in the piece that is being produced. A laser is typically used to sinter the media into a solid. FDM (FFF) generally has some restrictions on the slope of the overhang, and cannot produce unsupported overhangs.

[0007] There are many different FDM (FFF) 3D Printer configurations. The most popular arrangements are:

• Cartesian-XY-Head

• Cartesian-XZ-Head

• Delta

. Core XY

[0008] With the Cartesian-XY-head arrangement, the extruder head moves over the X and Y axis and the printing bed over the Z axis with a slow movement as the piece is printed. Z axis movement on a 3D printer with the Cartesian-XY-head arrangement is very precise and requires very low accelerations, but the printing bed needs to be lightweight in order to maintain accuracy.

[0009] The Cartesian-XZ-head arrangement differs from Cartesian-XY-head because it moves the printing bed over the Y axis and the extruder head over the X axis and the Z axis.

[0010] The main disadvantage of the Cartesian arrangements is the space occupation versus the printing area in the sense that the space occupation of the Cartesian 3D printer cannot be smaller than the printing area.

[0011] Delta 3D printers owe their name to the way the extruder head is supported by three arms in a triangular configuration. The benefit of a Delta arrangement is that the moving parts are lightweight and therefore limit the inertia. This results in faster printing with greater accuracy over a large open print volume. However, stability and freedom from vibration of the 3D printer, when moving a heavy print head on the end of spindly arms is a technical challenge. As the print head moves the distance of its filament from storage coil to head also changes, the tension created on the filament is another technical challenge to overcome to avoid affecting the print quality. Also, for 3D printing of large size objects, the printer must use longer arms that can support a heavy print head at the top. This will increase the risk of a gantry structure that flexes and vibrates in service, reducing print quality. Therefore, this design has mostly been favored as a means of gaining a large print volume without a large and heavy gantry for production of 3D objects.

[0012] Core XY is a Cartesian arrangement that is rapidly growing in popularity. The movement on the XY gantry depends on a combined effect of X and Y motors. CoreXY is a parallel manipulator system, which means that the motors on a CoreXY system are stationary. Parallel manipulator systems give more rapid acceleration than serial stackup configurations like Cartesian-XZ-head.

[0013] A handful of 3D printers use polar coordinates instead. Usually these are printers optimized to print objects with circular symmetry. These have a radial gantry movement and a rotating bed. Although there are some potential mechanical advantages to this design for printing hollow cylinders, their different geometry and the resulting non-mainstream approach to print planning still keeps them from being popular as yet. Although it is an easy task for a robot's motion planning to convert from Cartesian to polar coordinates, gaining any advantage from this design also requires the print slicing algorithms to be aware of the rotational symmetry from the outset.

[0014] A known robot type of movement arrangement is called SCARA which is an acronym for Selective Compliance Assembly Robot Arm or Selective Compliance Articulated Robot Arm. SCARA arrangement has an arm that is fixed in the Z-axis with rotational motion in the XY-axis. The arm has an additional XY-axis joint midway along its length. A linear actuator at the end of the arm provides Z-axis motion at 90° to the base’s mounting plane. An additional theta axis is supplied to the linear actuator to bring the total axis count to four. In many ways, the SCARA robot mimics the movement of a human arm. The maximum workspace envelope resembles a partial cylinder. SCARAs are generally faster and cleaner than comparable Cartesian robot systems. Their single pedestal mount requires a small footprint and provides an easy, unhindered form of mounting. All variants are modular by design, with differing linking arm lengths allowing users to specify the optimal reach required for a specific application. The robot is designed for a variety of general-purpose applications requiring fast, repeatable and articulate point-to-point movements. On the other hand, SCARAs can be more expensive than comparable Cartesian systems and the controlling software requires inverse kinematics for linear interpolated moves. Another disadvantage of the SCARA arrangement is that the weight is situated at the extremity of the two arms so each arm is subject to vibrations due to inertia. SCARA system is easily scalable but it uses two connected arms to achieve the movement, thus the articulated arm cannot cover the 360° printing area and the weight of the second arm makes it less stable and thus affecting the printer’s precision.

[0015] Efficient 3D printers and printing methods that address these conventional inefficiencies while utilizing a single compact 3D printer is therefore needed.

Summary of the invention

[0016] The present invention provides a solution to the above mentioned inherent problems associated with the known 3D printers and printing methods using the same. The main objective technical problem is how to allow continuous stable operations of a 3D printer in a linear and polar plane at the same time.

[0017] The main purpose of the present invention is to remedy the above mentioned drawbacks of the prior art by disclosing a 3D printer that can provide the stability of a Cartesian system, the space occupation of a SCARA using a 3-axis gantry system and thus obtaining a 3D object faster and with greater accuracy over a large open print area and/or volume.

[0018] This purpose is achieved in accordance with the invention having the characteristics of the independent claim 1.

[0019] The second main purpose of the present invention is to provide a method of operating a 3D printer to form a 3D object faster and with greater accuracy in a linear and polar plane at the same time.

[0020] This purpose is achieved in accordance with the invention having the characteristics of the independent claim 18.

[0021] Advantageous embodiments of the invention will appear from the dependent claims.

[0022] The 3D printer of the invention according to the independent claim 1 comprises: a printing base;

a central support rotatably mounted about a vertical axis (Z) on said printing base in a vertical orientation; at least one arm with a first end and a second end opposite the first end and wherein the first end is coupled to said central support in a translational manner along a distance (g) measured on the central support and being able to rotate with said central support about said vertical axis (Z) describing a circular arch with an angle (b) over a working area;

a printing tool support connected to said at least one arm in a translational manner along a distance (a) measured on the arm and laterally offset from said arm at a distance (doffset)

a 3D printing tool releasably mounted on said printing tool support to spread a build material via a printing head over said working area, wherein the build material is to be formed layer-by-layer into a three-dimensional (3D) object

wherein said printing head is configured to spread the build material over the working area in a controlled manner following a predetermined trajectory which combines the linear and angular movements of said at least one arm and said printing tool support with the angular movement of said central support.

Brief description of the drawings [0023]

Fig 1 depicts a front view of an embodiment of a 3D printing device in accordance with the present invention;

Fig. 2 depicts a detailed front view of an embodiment of a 3D printing device in accordance with the present invention;

Fig. 3 depicts a detailed front view of a central support according to an embodiment of a 3D printing device in accordance with the present invention;

Fig. 4 and Fig. 5 depict detailed front views of a motion transmitting assembly according to an embodiment of a 3D printing device in accordance with the present invention;

Fig. 6 and Fig. 7 depict detailed front views of a rod with cylindrical guiding pieces and a pinion gear assembly according to an embodiment of a 3D printing device in accordance with the present invention;

Fig. 8 depicts a perspective view of a rod with cylindrical guiding pieces and a pinion gear assembly according to an embodiment of a 3D printing device in accordance with the present invention;

Fig. 9 depicts a detailed perspective view of a pinion gear assembly according to an embodiment of a 3D printing device in accordance with the present invention;

Fig. 10 depicts a detailed top view of a printing tool support in the operating state according to an embodiment of a 3D printing device in accordance with the present invention;

Fig. 1 1 depicts a detailed top view of a printing tool support in the operating state including build material spool supports (one in the operating state and the other in a non-operating, folded state) according to an embodiment of a 3D printing device in accordance with the present invention;

Fig. 12 depicts a detailed front view of an arm according to an embodiment of a 3D printing device in accordance with the present invention; Fig. 13 depicts a detailed front view of a 3D printing tool according to an embodiment of a 3D printing device in accordance with the present invention;

Fig. 13a and Fig. 13b depict detailed views of an inside of a carriage block of a 3D printing tool according to an embodiment of a 3D printing device in accordance with the present invention;

Fig. 14 depicts a block diagram of an embodiment of a 3D printing device in accordance with the present invention;

Fig. 15 depicts a flow diagram of a method of operating a 3D printer that may be used by one or more embodiments of the present invention to form a 3D object;

Fig. 16 and Fig. 17 depict a XY axis system used to calculate the distance (doffset); Fig. 18 depicts a comparison chart of experimental data between the present invention and the prior art 3D printers.

Detailed description of embodiments of the invention

[0024] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and which only have an illustrative, not limiting value.

[0025] With reference to Figs. 1 to 18, a 3D printer (1 ) according to the present invention is disclosed comprising a printing base (2) which may be in any form that can be fixed to a working area (e.g. a table) for example by using fastening means (1 1 ) (e.g. nut and bolt) for providing stability for the 3D printer components. For example, the printing base (2) may be in the form of at least two stabilization supports (9) or a support (10). Preferably, the printing base (2) is made of aluminum which is known for its low density and its ability to resist corrosion.

[0026] Further, the 3D printer (1 ) comprises a central support (3) rotatably mounted about a vertical axis (Z) on said printing base (2) in a vertical orientation. The central support (3) may be in the form of a vertical column and may form a right angle with respect to the printing base (2). The central support (3) can rotate about a vertical axis (Z) on said printing base (2) without limiting the angle of rotation when the printing base (2) is in the form of a support (10) that can be fixed on the center of a working area. The central support (3) may use a slip ring technology, for example a through-hole slip ring (12), preferably a pancake slip ring (12) mounted on the printing base (2) (Fig. 4). This allows the power cables of the 3D printer to turn infinitely without tangling. Also, through-hole slip ring (12) can support precise power and signals transmitting and are designed for limited vertical space installation while horizontal space is less restrictive. Other advantages of using the slip ring technology include low torque, low friction, low electrical noise and durability. Referring to Figs. 1 to 3, when the printing base (2) is in the form of at least two stabilization supports (9) which can be fixed to an edge of a working area (e.g. a table), the angle of rotation of the central support (3) is limited to 270^Q.

[0027] The central support (3) is coupled to at least one arm (4) with a first end and a second end opposite the first end such that the arm (4) is angularly fixed at its first end with respect to the central support (3). That is, the at least one arm (4) cannot angularly rotate with respect to the central support (3). The at least one arm (4) is configured to move in a translational manner along a distance (y) measured on the central support (3), for example by operation of a gamma actuator (15), which may be affixed to the arm (4) and to rotate together with the central support (3) about said vertical axis (Z) describing a circular arch with an angle (b) over a working area. [0028] A printing tool support (5) is connected to said at least one arm (4) in a translational manner along a distance (a) measured on the arm (4) and laterally offset from said arm (4) at a distance (doffset) (Fig. 10).

[0029] The central support (3) may be connected to the printing base (2) preferably via a motion transmitting assembly comprising for example a rolling bearing mechanism (16) or ball bearing mechanism (16) and a cog-wheel (17). The cog wheel (17) is controlled by a beta actuator (14). The beta actuator (14) provides the torque input of the central support (3). The motion transmitting assembly may include also the slip ring technology for a 360° motion effect (Figs. 4 and 5). The central support (3) may have a cross-sectional shape formed by a hole or cut-out (hereinafter “hole”) within the interior of the central support (3) and the cross- sectional shape of the central support (3) may be for example circular or rectangular. In other embodiments, the hole may not be present.

[0030] In other preferred embodiments, the central support (3) may be in the form of two tubes (18) fixed to an intermediate plate (19) which is rotatably mounted about said vertical axis (Z) on said printing base (2) (Figs. 2 and 3). The tubes (18) may be fixed to the intermediate plate (19) via a pipe connecting means (20) such as a flange joint (20) (Fig. 9). The tubes (18) are connected in between them using for example a rod (21 ) with cylindrical guiding pieces (22) such as sleeve bushing (22) with a flange at each end of the rod (21 ) (Figs. 6 to 8). This allows a smooth gliding of the rod (21 ) and guiding pieces (22) along the central support’s (3) tubes (18). The tubes (18) may have at their top ends opposite the ends that are fixed to the intermediate plate (19), a handle (23) which may connect the tubes (18) in order to provide an easy handling of the 3D printer (1 ) (Figs. 1 to 3). The at least one arm (4) is then connected to said cylindrical guiding piece (22) such that a translational movement along said distance (y) measured on the central support (3) can be obtained when in use.

[0031] In a preferred example of the present invention (Figs. 10 to 12), the at least one arm (4) may be a metal frame (24), preferably stainless steel as it is very rigid and can limit the vibrations which occur during operation of the 3D printer (1 ). On this metal frame (24), a rail (25) may be connected, facing the working area, to allow the printing tool support (5) to achieve the linear movement along said distance (a) measured on the arm (4). An alpha actuator (13) turns one or two gears (281 ) of a pinion gear assembly (28) which in turn will drive one or two pulley (26) to guide a belt (27) along said frame (24) of the arm (4) from one end to the other opposite end of the arm (4) in a reciprocating manner to support the linear movement of the printing tool support (5) along the arm (4) (Fig. 8). The pinion gear assembly (28) is connected to the at least one arm (4) on its longitudinal axis. The metal frame (24) of the arm (4) supports said one or two pulley (26). The gears (281 ) of the pinion gear assembly (28) may move in opposite directions from one another to achieve a linear mirrored movement control (Fig. 8). This is used in some preferred examples of the present invention when two mirrored arms (4) may be connected to the central support (3) (Fig. 14).

[0032] The linear movement on the X, Y axis of the second arm (4) is mirrored from the first arm (4). The result is an actual axial symmetry when the center is coincident with the central support’s (3) center. Therefore, any operation done on one side of the central support (3) is replicated on the other side. For example, operators using the present invention can print two similar 3D objects at the same time also with the possibility to use different build/printing materials with or without having different colors without the need to stop the printing operation in order to change the color or the printing material. Therefore, the yield of the printing process is greatly increased.

[0033] The arm (4) may be generally rectangular in cross-section, though in other embodiments the arm (4) may have an alternative cross-section, for example a rounded cross-section or some other cross-section such as an l-shaped cross- section.

[0034] The arm (4) may include also a spiral cable (30) used to deliver data and power to a 3D printing tool (6) releasably mounted on the printing tool support (5) (Fig. 6 and 12). A spiral cable (30) is preferred because this shape allows it to extend and retract as needed, taking up less space when not in use. Spiral cables (30) are also less prone to tangling and knotting than straight shaped cables when the printing tool support (5) is moving along the arm (4).

[0035] The distance (y) measured on the central support (3) is preferably chosen between 0 cm to 60 cm, particularly preferred from 0 cm to 40 cm. However, the distance (y) can be easily increased if the height of the central support (3) is changed. These ranges allow for a major improvement concerning the printing area and/or volume compared to the volume of the 3D printer (1 ) (as shown in Fig. 18 and the following Table 1 ). The term “volume” must be understood as the amount of space taken up or occupied by the 3D printer (1 ).

[0036] The angle (b) is preferably chosen between 0 to 360^Q, but actual coordinates can be minus infinite to infinite, the infinite being the software limitation of the 3D printer (1 ).

Table 1 - Experimental data concerning the printing area and/or volume versus the volume of the 3D printer - comparison between the present invention and the prior art 3D printers

[0037] In other preferred embodiments of the present invention, the arm (4) may be folded using a lever (31 ) to unblock the arm (4) from a non-operating state (i.e. from the “closed position”), preferably in a plane parallel to said vertical axis (Z) and moving said arm (4) in the operating state (i.e.“open position”), preferably in a plane parallel to a working area (Figs. 8 to 10). When having two mirrored arms (4) connected to the central support (3), one of said arms (4) may be folded into the non-operating state during the operation of the other arm (4) which is moved in the operating state (Fig. 1 1 ). Also, the arms (4) may be folded for space optimization when the 3D printer is not in use.

[0038] The distance (a) measured on the arm (4) starting from its first end towards its second end opposite the first, wherein the first end is coupled to said central support (3) is preferably chosen between 0 cm to 45 cm, particularly preferred between 0 cm to 20 cm. The distance (a) can be easily increased by adding stronger and longer arms (4) operated by powerful alpha actuators (13). Thus, the printing area and/or volume will be considerably increased (see Table 1 above and Fig. 18). The present invention has a physical limitation with regards to the working area meaning that the central support’s (3) footprint may be for example a cylindrical footprint preferably with a maximum diameter of 25 cm which is a non-printing working area. Also, having different arms (4) lengths and different distance (a), the present invention can print 3D objects of different sizes.

[0039] The distance (doffset) is a distance measured laterally between a 3D printing tool support (5) and said arm (4) on the X, Y, Z axis or as a complex offset calculated on the Y and X axis. The distance (doffset) is preferably chosen below 10 cm, which is not to be regarded as a physical limitation. There is a need to reduce this distance (doffset) in order to simplify the calculation regarding the position of the center of the 3D printing tool (6), where a printing head (7) is usually located, when considering the position of the arm (4) (Figs. 10 and 1 1 ). As stated previously, the central support (3) rotates with an angle (b) wherein the 3D printing tool support (5) moves in a translational manner on the arm (4) along a distance (a). The mix of the linear and angular moves allow for the printing tool support (5) to be moved everywhere on the circle described over the working area (the only blocked area is the central support’s (3) footprint). Standard Cartesian to Polar conversion cannot be used because the offset of the 3D printing tool support (5) must be calculated also (the 3D printing tool support (5) is not totally aligned with the longitudinal axis of the arm (4) so the angle (b) cannot be directly calculated). Usual solutions require to place an axis of the C,U,Z system as a reference - therefore, angle (b) becomes 0°. This is not possible in the present invention system due to the constant combined movements of the central support (3), the at least one arm (4) and the printing tool support (5). No axis can be fixed to simplify the calculation.

[0040] The present invention solved the above mentioned problem by using the calculation with vectors (please refer to Figs. 16 and 17):

// x,y are the coordinates of the printing head (7)

//if an offset (doffset) is present, then the position of the printing tool support (5) must be calculated

float x = cartesian_mm[X_AXIS];

float y = cartesian_mm[Y_AXIsj;

float offx = 0; // printing tool support (5) + central support (3) offset on the arm (4) float offy = 0; // printing tool support’s (5) offset

float r=0;

float 0=0;

float 02=0;

float a=0;

float b=0;

//polar conversion of x and y with no offset involved r=sqrt(x²+y²); //linear conversion of the printing head (7) position (x,y)

9=atan2(y,x); //angular conversion of the printing head (7) position (x,y)

//offset impact calculation

a=sqrt(r²-offy²)-offx; //linear move

92=atan2(offy, offx+a);

b=q-q2; //angular move measured in radian

[0041] The arm (4) must be parallel with the printing tool support (5). A calibration is needed to reduce measurement error when calculating the offset (doffset). This may be done for example by turning an adjusting screw (32) to level the arm (4) (Fig. 9).

[0042] The printing tool support (5) may be connected to at least one arm (4) by means of a carriage block (33) (Fig. 13). The belt (27) supports the carriage block (33) which may include an aluminum block assembly (331 ) with a magnet (332) and an electronic connection device (34) such as pogo pins (34) for establishing a connection between a controller (35) coupled to the 3D printer’s (1 ) alpha, beta and gamma actuators (13, 14, 15) and a data storage (36) which ultimately gives signals to said actuators (13, 14, 15) to move the printing tool support (5), the central support (3) and the at least one arm (4) in a controlled manner following a predetermined trajectory (Figs. 13a and 13b).

[0043] The controller (35) may be simple (e.g. a fixed mechanical or electronic system), software-based (e.g. a printer driver, robot control system), a human, or any other input. The controller (35) is coupled to the 3D printer’s (1 ) alpha, beta and gamma actuators (13, 14, 15) which are responsible for moving and controlling the printing tool support (5), the central support (3) and the at least one arm (4). The control signal received by the actuators (13, 14, 15) may be electric voltage or current, pneumatic or hydraulic pressure, or even human power. The main energy source of the actuators (13, 14, 15) may be an electric current, hydraulic fluid pressure, or pneumatic pressure.

[0044] A correspondent aluminum block assembly (371 ) with a magnet (372) is included in the 3D printing tool (6) to easily mount and/or dismount said 3D printing tool (6). The correspondent aluminum block assembly (371 ) may include alignment tubes (381 ) that are remotely aligned with corresponding fastener holes (382) in the carriage block (33) (Figs. 13a and 13b). A lever (39) may be used to easily dismount the 3D printing tool (6).

[0045] Well-known 3D printers usually have a printing tool which is mechanically soldered or fixed or screwed on the printing tool support and therefore it is very difficult to replace the printing tool with another.

[0046] At least one build material spool support (40) may be connected at the top extremity of the central support (3) to store and provide a build material (8) to the 3D printing tool (6) (Figs. 1 , 2 and 1 1 ). It may comprise an arm (401 ) and at least one spool (402) rotatably mounted at one end of said arm (401 ) opposite to the second end which is connected to the top extremity of the central support (3). The at least one build material spool support (40) may be folded in a rotatable manner about a horizontal axis (Y1 , Y2) in a parallel plane with the vertical axis (Z) along the central support (3) when not in use.

[0047] The build material (8) may be in the form of: a filament, a powder-based build material, a liquid, a paste or a gel. In other examples, the build material (8) may be used with other suitable build materials, with suitable modification if appropriate.

[0048] The preferred material used for the build material spool support (40) is plastic. [0049] When using two mirrored arms (4), two build material spool supports (40) are needed. The printing is done twice faster compared to other known 3D printers and without the need to change filaments (8) when printing is done with two different build materials (8) with or without having different colors at the same time. Changing filaments (8) is often a time consuming process and printing operation must be stopped.

[0050] The 3D printing tool (6) is configured to spread build material (8) via a printing head (7) over a working area. The build material (8) is to be formed layer-by-layer into a three-dimensional (3D) object. For example, a continuous strand of build material (8) may flexibly extend from the build material spool support (40) to the top of the 3D printing tool (6). To apply the build material (8) over the working area or over a layer of a 3D object to be formed, one or more components of the 3D printing tool (6) such as the printing head (7) or a separate element (41 ) of the 3D printing tool (6) such as a heating cartridge (41 ) which is coupled with the printing head (7), may be heated to a temperature sufficient to melt the build material (8). This operation is done in a melting zone. Then, when the 3D printing tool (6) is in the appropriate location, it begins to spread the build material (8) from the melting zone over the working area. A motor may rotate a gear to feed build material (8) into the the heating cartridge (41 ). This process may continue in a controlled manner following a predetermined trajectory which combines the linear and angular movements of said at least one arm (4) and said printing tool support (5) with the angular movement of said central support (3).

[0051] A method of operating a three-dimensional (3D) printer according to the present invention, to form a 3D object according to independent claim 18 comprises the following steps: a) accessing data of a 3D object to be printed and dividing a 3D object’s digital model into layers of determined width;

b) providing build material to a 3D printing tool;

c) generating Cartesian moves for each layer and commands for each generated Cartesian move by means of a controller coupled to alpha, beta and gamma actuators of said 3D printer;

d) moving said printing tool support, central support and at least one arm respectively by means of said alpha, beta and gamma actuators at a point (So) where printing of the 3D object is to start;

e) preparing the printing head of said 3D printing tool by warming it up;

f) sending next command by means of said controller;

g) converting Cartesian coordinates of said generated Cartesian moves into polar and linear coordinates;

h) moving said at least one arm to a level position by means of said gamma actuator;

i) moving said central support to a polar coordinate by means of said beta actuator;

j) moving said printing tool support and said 3D printing tool to a linear coordinate by means of said alpha actuator;

k) depositing a build material from said printing head at predetermined polar and linear coordinates according to step g) over a working area in a controlled manner;

L) repeating steps f)-k) until the 3D object is formed. [0052] Fig. 15 depicts a flow diagram of a method of operating a 3D printer (1 ) that may be used by one or more embodiments of the 3D printer (1 ) to form a 3D object.

[0053] With reference to the method (block 100) depicted in Fig. 15, an input design file, which may be an output of a computer aided design (CAD) program or some other design program, may be digitally interpreted by one or more elements of a computer software stored on a server (29) connected to a controller (35) which is coupled to a 3D printer (1 ). The controller (35) executes the instructions to access data of a 3D object to be printed (block 101 ) and to split the 3D object’s digital model into layers of determined width (block 102). The data of the 3D object to be printed (block 101 ) may include information pertaining to the locations on each of the respective build material layers (block 102) at which melted build material (8) is to be deposited during a printing operation.

[0054] At block 103, the controller (35) may execute the instructions to cause the build material source (40), for example a build material spool support (40) connected to a motor and a gear assembly, to feed or provide build material (8) into the heating cartridge (41 ).

[0055] Then, the controller (35) generates Cartesian moves for each layer (block 104) and generates commands for each Cartesian move (block 105).

[0056] In order to obtain the reference values/ the controller (35) further executes the instructions to move each of the following components of the 3D printer (i): printing tool support (5), central support (3) and at least one arm (4) respectively using the alpha, beta and gamma actuators (13, 14, 15) at the point where printing of the 3D object is to start (S₀) (block 106).

[0057] At block 107, the controller (35) executes the instructions to cause the heating cartridge (41 ) of a 3D printing tool (6) to warm up the printing head (7) and to send next command (block 108).

[0058] The controller (35) further converts the Cartesian coordinates of the Cartesian moves generated previously at block 104 into polar and linear coordinates using an algorithm based on the calculation provided in paragraph [0040] of the present disclosure (block 109) to determine the coordinates where the build material (8) is to be deposited or spread.

[0059] Then, the at least one arm (4) is moved to the level position by the gamma actuator (15) (block 1 10), the central support (3) is moved to the polar coordinate by the beta actuator (14) (block 1 1 1 ) and the printing tool support (5) together with the printing 3D tool (6) is moved to the linear coordinate by the alpha actuator (13) (block 1 12).

[0060] At block 1 13, the controller (35) executes the instructions to control the printing head (7) to deposit or to spread a build material (8) at the predetermined coordinates identified at block 109 over a working area in a controlled manner.

[0061] If an additional layer is needed (block 1 15), the process is repeated from block 108 onwards to form additional build material (8) layers of the 3D object until the controller (35) determines that no additional layers are to be added at block 1 15, at which point the printing process may end as indicated at block 1 16.

[0062] In another embodiment of the present invention, when two mirrored arms (4) are used, after the step depicted at block 1 13, the controller (35) selects the mirror printing process (block 1 14) and executes the instructions to control the second printing head (7) to deposit or to spread a build material (8) at the predetermined coordinates identified at block 109 for the mirrored arm (4) over a working area in a controlled manner (block 1 17).

[0063] At block 1 17, the controller (35) may execute the instructions to control the second arm (4) and to cause the second printing tool support (5) to move on the second arm (4), independently with respect to the first arm (4) such that more than one 3D objects can be printed on the working area at the same time.

[0064] Also, the second printing tool support (5) always has a linear mirrored movement even when the mirror printing process is not activated and even when the arm (4) is folded along the central support (3) (Figs. 1 and 2). This is due to the fact that the two gears (281 ) of a pinion gear assembly (28), that is connected to said at least one arm (4) on its longitudinal axis, always move in opposite directions from one another to achieve the linear mirrored movement control. A mechanical calibration of the printing tool support’s (5) position needs to be performed before the activation of the mirror printing process.

[0065] What has been described and illustrated herein is an example of the disclosure along with some of its optional features. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. The scope of the disclosure is intended to be defined by the following claims.

Claims

1. A three-dimensional (3D) printer (1 ) comprising:

- a printing base (2);

- a central support (3) rotatably mounted about a vertical axis (Z) on said printing base (2) in a vertical orientation;

- at least one arm (4) with a first end and a second end opposite the first end and wherein the first end is coupled to said central support (3) in a translational manner along a distance (g) measured on the central support (3) and being able to rotate with said central support (3) about said vertical axis (Z) describing a circular arch with an angle (b) over a working area;

- a printing tool support (5) connected to said at least one arm (4) in a translational manner along a distance (a) measured on the arm (4) and laterally offset from said arm (4) at a distance (doffset);

- a 3D printing tool (6) releasably mounted on said printing tool support (5) to spread a build material (8) via a printing head (7) over said working area, wherein the build material (8) is to be formed layer-by-layer into a three- dimensional (3D) object and wherein said printing head (7) is configured to spread the build material (8) over the working area in a controlled manner following a predetermined trajectory which combines the linear and angular movements of said at least one arm (4) and said printing tool support (5) with the angular movement of said central support (3).

2. A three-dimensional (3D) printer (1 ) according to claim 1 further comprising a controller (35) coupled to:

- a first drive system (13), preferably an alpha actuator (13) to move and control said printing tool support (5);

- a second drive system (14), preferably a beta actuator (14) to move and control said central support (3) independently from said first drive system (13) and

- a third drive system (15), preferably a gamma actuator (15) to move and control said at least one arm (4) independently from said first drive system (13) and said second drive system (14).

3. A three-dimensional (3D) printer (1 ) according to claim 2 wherein said first drive system (13) is preferably connected to said central support (3) and a pinion gear assembly (28) is preferably connected to said at least one arm (4) on its longitudinal axis and in contact with said first drive system (13) such that at least one gear (281 ) of said pinion gear assembly (28) is configured to transmit motion when actuated.

4. A three-dimensional (3D) printer (1 ) according to claim 3 wherein said at least one gear (281 ) is configured to drive preferably at least one pulley (26) which preferably is configured to guide a belt (27) along said at least one arm (4) from said first end to said second end opposite the first end in a reciprocating manner to enable said printing tool support (5) to move along said at least one arm (4).

5. A three-dimensional (3D) printer (1 ) according to any of the preceding claims wherein preferably a first and a second said arms (4) are provided in a mirrored arrangement with respect to a symmetry axis corresponding to said vertical axis (Z) such that a linear movement of said second arm (4) on a X and/or Y axis is mirrored from said first arm (4).

6. A three-dimensional (3D) printer (1 ) according to claim 5 wherein two said gears (281 ) of said pinion gear assembly (28) are configured to move in opposite directions from one another.

7. A three-dimensional (3D) printer (1 ) according to any of the preceding claims wherein:

- said distance (y) measured on the central support (3) is preferably chosen between 0 cm to 60 cm, particularly preferred between 0 cm to 40 cm;

- said angle (b) is preferably chosen between 0^Q to 360^Q;

- said distance (a) measured on the arm (4) starting from its first end towards its second end opposite the first, wherein said first end is coupled to said central support (3) is preferably chosen between 0 cm to 45 cm, particularly preferred between 0 cm to 20 cm and

- said distance (doffset) is preferably chosen below 10 cm.

8. A three-dimensional (3D) printer (1 ) according to claim 7 when dependent on claim 5 or claim 6 wherein said first and second arms (4) have different arm (4) lengths with different said distance (a) measured on said arms (4).

9. A three-dimensional (3D) printer (1 ) according to any of the preceding claims wherein said central support (3) is rotatably mounted on said printing base (2) preferably by means of a motion transmitting assembly comprising:

- a rolling bearing mechanism (16) or a ball bearing mechanism (16) including a cog-wheel (17) controlled by said second drive system (14) and

- a through-hole slip ring (12) for example a pancake slip ring (12),

said motion transmitting assembly being interconnected between said central support (3) and said printing base (2).

10. A three-dimensional (3D) printer (1 ) according to any of the preceding claims wherein said printing base (2) is preferably in any form that can be fixed to a working area, for example at least two stabilization supports (9) or a support (10) and wherein said printing base (2) is preferably made of metal, particularly preferred of aluminum.

1 1 . A three-dimensional (3D) printer (1 ) according to any of the preceding claims wherein said central support (3) is preferably a vertical column (10)

or

a support having two tubes (18) fixed on an intermediate plate (19), said tubes (18) being connected between them, for example by using a rod (21 ) with cylindrical guiding pieces (22) such as sleeve bushing (22) with a flange at each end of said rod (21 ) to connect said at least one arm (4).

12. A three-dimensional (3D) printer (1 ) according to any of the preceding claims wherein said printing tool support (5) is preferably connected to said at least one arm (4) by means of a carriage block (33) supported by said belt (27) and wherein said carriage block (33) comprises an aluminum block assembly (331 ) having a magnet (332) and an electronic connection device (34) which said aluminum block assembly (331 ) is configured to connect a correspondent aluminum block assembly (371 ) included in said 3D printing tool (6) and having a magnet (372) and alignment tubes (381 ) that are remotely aligned with corresponding fastener holes (382) provided in said carriage block (33).

13. A three-dimensional (3D) printer (1 ) according to any of the preceding claims wherein said central support (3) comprises preferably at least a build material spool support (40) connected to said central support’s (3) top extremity to store and provide said build material (8) to said 3D printing tool (6).

14. A three-dimensional (3D) printer (1 ) according to claim 13 wherein said at least a build material spool support (40) preferably comprises an arm (401 ) and at least one spool (402) rotatably mounted at a first end of said arm (401 ) opposite to a second end which is connected to said central support’s (3) top extremity and wherein said build material spool support (40) is configured to fold in a rotatable manner about a horizontal axis (Y1 , Y2) in a parallel plane with said vertical axis (Z) along said central support (3) when not in use.

15. A three-dimensional (3D) printer (1 ) according to any of the preceding claims wherein said at least one arm (4) further comprises a lever (31 ) configured to unblock said arm (4) from a non-operating state, preferably in a plane parallel to said vertical axis (Z) and moving said arm (4) in an operating state, preferably in a plane parallel to a working area.

16. A three-dimensional (3D) printer (1 ) according to any of the preceding claims wherein said at least one arm (4) further comprises a spiral cable (30) suitable to deliver data and power to said 3D printing tool (6).

17. A three-dimensional (3D) printer (1 ) according to any of the preceding claims wherein said at least one arm (4) is preferably made of metal, particularly preferred of stainless steel.

18. A method of operating a three-dimensional (3D) printer (1 ) according to any of the preceding claims 1 to 17, to form a 3D object, said method comprising the following steps:

a) accessing data of a 3D object to be printed and dividing a 3D object’s digital model into layers of determined width;

b) providing build material (8) to a 3D printing tool (6);

c) generating Cartesian moves for each layer and commands for each generated Cartesian move by means of a controller (35) coupled to alpha, beta and gamma actuators (13, 14, 15) of said 3D printer (1 ); d) moving said printing tool support (5), central support (3) and at least one arm (4) respectively by means of said alpha, beta and gamma actuators (13, 14, 15) at a point (So) where printing of the 3D object is to start;

e) preparing the printing head (7) of said 3D printing tool (6) by warming it up;

f) sending next command by means of said controller (35);

h) moving said at least one arm (4) to a level position by means of said gamma actuator (15);

i) moving said central support (3) to a polar coordinate by means of said beta actuator (14);

j) moving said printing tool support (5) and said 3D printing tool (6) to a linear coordinate by means of said alpha actuator (13);

k) depositing a build material (8) from said printing head (7) at predetermined polar and linear coordinates according to step g) over a working area in a controlled manner;

L) repeating steps f)-k) until the 3D object is formed.

19. A method according to claim 18, wherein a first and a second mirrored arm (4) are provided, further comprising the following steps:

m) selecting a mirror printing process after step k) by means of said controller (35) and;

n) controlling a second printing head (7) of a second 3D printing tool (6) mounted on a second printing tool support (5) connected in a translational manner to said second mirrored arm (4) to deposit a build material (8) at predetermined polar and linear coordinates according to step g) for said second mirrored arm (4) over a working area in a controlled manner;

wherein step n) is performed independently from said first mirrored arm (4).

20. A method according to claim 19, further comprising the step of performing a mechanical calibration of the printing tool support’s (5) position before step m).