The subject of the invention is a printer for three-dimensional printing designed for fabrication of three-dimensional products of light-cured (photo-polymerising) materials with the use of SLA/D LP technology based on transmission of light through optical fibres.

Known and universally utilised printing with the use of 3D printers is a process of production of digitally developed three-dimensional products in which the technology based on melted thermoplastic material is employed known as the Fused Filament Fabrication (FFF). Printing is carried out by means of deposition of successive layers with shapes designed specifically for given product. The technology consists in supplying a filament of a FFF material heated up to a semi-liquid state to head of a 3D printer moving in three planes X, Y, Z. The thermoplastic materials used in the 3D printing process can be thermoplastic material of any type in the form of a cord known as the filament wound onto a spool, such filament being then deposited in layers or point-like, whereas the process of deposition is usually realised in a chamber capable to maintain a temperature allowing to form the plastic material thermally. Local temperature of the plastic deposited in layers just after leaving the nozzle is usually close to its melting point.

In the course of printing with the use of a 3D printer, one critical issue is to maintain appropriate conditions inside the printout chamber, including proper temperature in the working chamber and temperature of the working platform.

With the development of the technology of printing three-dimensional objects with the use of 3D printers, numerous different engineering processes is currently used to fabricate physical three-dimensional models, including the process consisting in conversion of design information containing in digital 3D models created by a software, usually of CAD type, into plurality of thin (quasi-two-dimensional) cross-sectional layers which are stacked one on another. Moreover, printing module of a 3D printing device can be also displaced above the base along plane X,Y by reference to co-ordinates C,U,Z of the device constructed out of virtual design data of 3D models in a way allowing to extrude or deposit a material so that consecutive layers reproduce correct shapes of cross-sections of the fabricated product. The deposited material may then cure in a natural way or be cured by e.g. a high-power light source to create the required cross-section layer. Then, moving the printing module of the 3D printing device along“Z” axis with respect to consecutive layers, a plurality of layers of a given cross-section can be gradually stacked along“Z” axis thanks to which the material may be put together into a three-dimensional object, layer by layer. In case of forming a three-dimensional object layer by layer using a source of light to cure a deposit of material, printing module of the 3D printing device is adapted for being immersed in liquid material containing a light-sensitive resin contained in a tank, and source of light in X,Y plane irradiates the material contained in the liquid which can be cured and deposited on movable platform of the printing module of the device. This way, by moving the movable platform of the printing module along the“Z” axis, the material contained in the liquid can be cured layer by layer and deposited in the form of a stack creating thus a three-dimensional object. However, in case forming a three-dimensional object this way, there is a risk of adhesion of the cured material to bottom of the resin- containing tank an then irradiation with the source of light may change and affect further results of the forming process. From a publication on Internet page http://fabrvkator.pl/seasidecustoms/cristelia-drukarka-slalc d-dla-zvwicv-daylight/ known is a SLA/LCD resin printer by Cristelia comprising a cuboidal frame provided in its lower part with a moulded piece equipped with a light-curing resin storage container and a liquid crystal display (LCD) situated under the container and coupled with an upper holder via linear guides. The resin is cured with the use of blue light (wavelength 470-500 nm) coming from a LCD screen disposed under storage container for the resin.

From patent description CN 103722745 A known is a fast method for forming objects out of light-curing resin based on the principle of selective light transmission on a liquid crystal display (LCD), which comprises the following steps:

- a step of placing a reservoir with resin above the LCD screen, exposing the resin layer by layer by means of the contact exposure method, and placing a Fresnel lens between the screen and the light source so that thickness of each layer of resin in the course of its curing was 20(M-00 pm, and the period of curing of a single layer ranged from 1 second to 8 seconds;

- a step of moving the cured resin plate supporting the mould by 200-400 pm, respectively, under the control of a system of motion along“Z” axis;

- a step of rinsing the module in an organic solvent after completion of the full curing process.

The source of light in this method are high-power LEDs and glass substrate covered with silica gel is situated on bottom of the tank with resin thanks to which the resin can be relatively separated from the substrate, whereas the light source in the form of LED(s) can be easily replaced and its power controlled, while different types of resins can be formed and cured.

From patent description of invention WO 2014126830 known is a method and a device for fabrication of three-dimensional products comprising the following steps:

- providing a carrier and a build plate comprising an semi-permeable member comprising a build surface and a feed surface, with the build surface and the carrier defining a build region therebetween and with the feed surface in fluid contact with a polymerisation inhibitor;

- filling the build region with a polymerisable liquid contacting said build segment of the 3D apparatus; - irradiating the build region through the build plate to produce a solid polymerised region in the build region, with a liquid film release layer comprised of the polymerisable liquid formed between the solid polymerised region and the build surface, the polymerisation of which liquid film is inhibited by said polymerisation inhibitor; and then

- advancing the carrier with the polymerised region adhered thereto away from the build surface on the build plate to create a subsequent build region between the polymerised region and the top zone of the build plate to fill the next region of fabrication of the object with the polimerisable liquid described in the first step.

The above-quoted description of invention contains also specification of an apparatus for realisation of the method comprising a significant number of component elements interconnected functionally with each other, where high-power radiation such as laser light and UV radiation was used.

From patent description US 5344298 known is also an apparatus for making three- dimensional objects by stereolithography with the use of an UV laser by creating a cross- sectional pattern of the object to be formed at a selected surface of a fluid medium capable of altering its physical state in response to appropriate synergistic stimulation by impinging radiation, particle bombardment or chemical reaction, successive adjacent laminae, representing corresponding successive adjacent cross-sections of the object, being automatically formed and integrated together to provide a step-wise laminar build-up of the desired object. As a result of such process, a three-dimensional object is formed and drawn from a substantially planar surface of the fluid medium during the forming process.

Known also from description of Polish patent application No. P.416429 is a 3D printer designed for fabrication of three-dimensional physical objects with the use of stereolithography (SL). The printer comprises a closed cabinet impenetrable for light housing: an open tank with transparent bottom filled with photo-polymerising resin; a movable support on lower surface of which the printed three-dimensional object comes into existence; and an equalisation reservoir with the photo-polymerising resin. Under transparent bottom of the open tank there is a source of light in the form of display of a mobile device (cellular phone), and inner side of the transparent bottom made of quartz glass is covered with a separation film (of PVC with an admixture of silicone) separating the transparent bottom from the photo-polymerising resin. Further, between the transparent bottom of the tank and the light source there is a system of converging lenses of F-Theta type enlarging the image projected by the light source. As the 3D printout develops, the movable support is raised allowing thus creation of consecutive layers of the 3D printout, and the depletion of photo-polymerising resin in the open tank is topped up automatically from an equalising reservoir.

Further, from patent description No. CN 104325642 known is a high-precision 3D printer using a resin cured by means of a source of light in the form of LED provided with an optical lens situated between the periphery of the LED and a Fresnel lens which covers a LCD screen arranged in an outer frame, whereas liquid resin is stored in the liquid storage tank above the LCD screen and the liquid storage tank bottom plate is covered with a high light transmission release type membrane, while the print platform is situated in upper portion of the tank. From patent description of Polish invention filed under No. P.416846 known is also a 3D printer with a working platform for three-dimensional printing using the technology of deposition of a melted material. The printer comprises a heated working chamber inside which there is a working platform is fixed radially- vertically on a plurality of linear drives and a printing head mounted on a plurality of linear drives and displaced in horizontal plane. The working platform is mounted preferably on three linear drives in the form of screw drives. On the other hand, the printing head is fixed on two linear drives in the form of screw drives to enable displacement in one of directions of horizontal plane and on a single screw linear drive to enable displacement in the second of directions of the horizontal plane. The heated working platform of the 3D printer according to that invention ensures optimum adhesion of the printed object to the substrate thanks to heating of the working plate top of the working platform. Further, heating the working chamber and controlling the printout cooling process minimises and stabilises internal stresses in the printed object. The design of the working platform allows to use the heat from the heating plate to rise and stabilise temperature of working platform and working chamber of the 3D printer. The disclosed solution assures precise division of heat energy between the working platform and the working chamber. The use of temperature sensors integrated into the working chamber and the working platform and connected with the control system offers the possibility to monitor and control both the heating and the cooling process. The use of an agitation fan installed in the working chamber increases additionally uniformity of temperature distribution inside the working chamber volume which has a significant effect on printout quality. Application of a heating plate powered with high-voltage direct current in the working platform allowed to reduce thickness of the element and thus thickness of the platform itself which had a favourable effect on compactness of the whole 3D printer.

From patent description of invention filed under No. PL/EP 2083992 known is also an apparatus for production of a three-dimensional object based of photo-curing induced by laser or masked irradiation with the use of a projection unit under which, in a container, there is a liquid photo-polymerising material in which a support plate is situated capable to be raised in vertical direction, where level of the liquid is detected with the use of a detector and is topped up from an equalising reservoir of the liquid. Position of the support plate is determined on current basis as a result of being connected with an encoder which allows the motion of the plate and the liquid container to be controlled by a control unit and a stepper motor.

The objective of the present invention is to provide a new, unknown in the prior art, structure of a printer for three-dimensional (3D) printing to be used for fabrication of three- dimensional products of a light-curing (photo-polymerising) material as a result of supplying the light necessary for curing in the form of electromagnetic radiation by a suitable set of optical fibres and a device generating the radiation/light, which can be e.g. a LCD screen, light emitting diodes, a projectors, or other sources. A further objective of the invention is to provide a new structure of the storage container unit of the printer based on optical fibres arranged suitably with respect to each other and co-operating with working platform of the printer.

The subject-matter of the printer for three-dimensional printing according to the invention consists in that the storage container unit of the printer comprises a rectangular frame with peripheral offsets, the interior of which is formed by single-mode optical fibres arranged symmetrically to each other, each fibre comprising a light-transporting core and a coating impenetrable to light, where upper ends of the optical fibres are joined permanently with lenses under which a stabilising mesh is situated, while upper ends of the optical fibres are straight-through fixed in a stiffening silicone layer impenetrable to light. Lower surface of the frame and the silicone layer are flush with one another and the optical fibres protrude by length L = 0-1000 cm below the flush surfaces resting directly on a source of light situated in the housing forming thus a screen-like structure. Further, above the silicone layer and between rows of optical fibres, there are conduits arranged alternately with straight-through holes provided along the whole of their lengths to facilitate distribution of the light-curing material, while ends of these conduits are connected to conduits supplying and returning the light-curing material to the reservoir of the controlling-pumping unit. It is favourable when below the screen comprising the source of light there is a frame-shaped rectangular insulating element adhering to the screen and situated on a frame-shaped rectangular base with mounting seats, cylindrical pins mounted in the seats, and vibration coils fixed on the pins, whereas ends of these coils are situated in grooves of the frame and are connected electrically with conductors of a controller controlling operation of the printer. It is also favourable when diameter of optical fibres is from 1 pm to 1 cm, and lenses situated on the fibres are converging or diverging lenses with diameters equalling from 1.0 to 1.2 of diameter of the optical fibres.

It is also favourable when the source of light is a LCD or LEDs or a projector or UV lamps or laser diodes or optical radiation sources or radioactive sources, and the light- curing material is a resin or a composite material.

The use of optical fibres in the printer according to the invention allows to transmit light with much higher intensity compared to 3D printers known in the prior art, as a result of which larger thickness of individual layers is obtained and larger number of layers cured in significantly shorter time.

Moreover, the use of optical fibres in the 3D printer ensures even inflow of light-curing material resulting thus in increased productivity and acceleration of the process of printing the required product.

The subject-matter of the invention is illustrated in drawings showing a number of its embodiment, of which Figs. 1-14 show the first version of the printer for 3D printing in which the source of light is situated directly under a layer of silicone with optical fibres planted in it, whereas Fig. 1 shows the printer for 3D printing with open glazed doors of its cabinet housing, in the perspective view; Fig. 2— functionally linked working units of the printer as seen after removing them from the cabinet housing, in the perspective view; Fig. 3— the same working units, in the front view; Fig. 4— the storage container unit of the printer, in the top view; Fig. 5— the same storage container unit, in vertical cross-section along line A-A; Fig. 6— exploded view of the storage container unit together with its, in perspective view; Fig. 7— enlarged detail“C” of a fragment of container, optical fibres, and the screen, in vertical cross-section; Fig. 8— enlarged detail“D” of the storage container unit in its portion concerning location of elbows supplying light-curing material, a mesh stabilising vertical position of optical fibres, optical fibre lenses, and conduits distributing the material among optical fibres, in the top view; Fig. 9— enlarged detail“E” of the storage container unit with a fragment of side portion of the container, optical fibres, the screen, the insulating plate, and base of the container, in vertical cross-section; Fig. 10 — enlarged detail“F” of the storage container unit showing the opposite side portion of the container, the screen, and the storage container base constituting one of its comer provided with a pin with a vibration coil, in vertical cross-section; Fig. 11— enlarged detail“G” of one of comers of the storage container base together with a pin mounted in it and a vibration coil fixed on the pin, in the perspective view; Fig. 12— enlarged detail “H” of the left-hand-side trolley carriage guiding sub-assembly, in the perspective view; Fig. 13— enlarged detail“I” of analogous right-hand-side trolley carriage guiding sub- assembly, in the perspective view with a portion if the sub-assembly removed for better view; Fig. 14— cross-section B-B of the storage container unit shown in Fig. 7. Figs. 15- 17 depict the second version of embodiment of the printer for 3D printing in which the light source is situated under optical fibres planted in and passing through a layer of silicone, of which Fig. 15 shows the storage container unit of the printer, in the top view; Fig. 16— the same storage container unit in vertical cross-section along line K-K; and Fig. 17— enlarged detail“F” of the storage container unit with a fragment of side portion of the container, optical fibres, the screen, the insulating plate, and the storage container base, in vertical cross-section.

The printer for 3D printing comprises a cuboidal cabinet housing 1 with glazed doors, a plate-shaped support base 2 situated inside and joined with the housing, a working platform assembly 3 a storage container unit 4 joined with the support base, and a controlling-pumping unit 5 fixed to floor of the cabinet housing 1 and supplying the lightcuring material to working space of the storage container unit 4. The plate-shaped support base 2 of the printer has the shape of a rectangular plate provided, on both of its two shorter sides, with vertical offsets 6 with mounting holes 7 separated from each other by U- shaped recesses 8, and its upper surface is provided with a cuboidal seat 9 with a lower offset 10; further, the base has rounded comers 11 and straight-through rectangular recesses 12 provided in said comers, whereas vertical offsets 6 of the support base 2 are fixed, by means of mounting holes 7 and screws 13, to both of the side walls 14 of the cabinet housing 1. The working platform assembly 3 comprises two guiding-driving sub- assemblies 15 driving trolley carriages 16 joined with the working platform 17. Each of these guiding-driving sub-assemblies 15 has two vertically oriented monolithic profiled columns 18 with flat outer offsets 19 and with rounded guides 20 and further has driving screws 21 disposed between said columns, also oriented vertically and having nuts 22 screwed onto them, whereas upper ends of these columns and screws are topped with horizontally situated plate-shaped elements 23, and their lower ends topped with analogous plate-shaped elements 24, while both ends of the screws are mounted rotationally in bearings 25 fixed in both of the two plate-shaped elements 23 adjacent to inner surface of ceiling wall 26 of the cabinet housing 1 as well as in plate-shaped elements 24 to each of lower surfaces of which fixed are two vertically situated plate-shaped elements 27 joined with each other with horizontal plate-shaped elements 28 forming thus cuboidal chambers 29, disposed on plate-shaped support base 2 in U-shaped recesses 8 and between vertical offsets 6 of the base. Moreover, flat outer offsets 19 of the profiled columns 18 are fixed, bye means of screws disposed in their mounting holes 30, to both vertical walls 14 of the cabinet housing 1, while lower ends of the drive screws 21 protrude beyond the lower plate-shaped elements 24 and through clutches 31 provided in the cuboidal chambers 29 are coupled with their electric drive motors (not shown in the drawings) situated in cuboidal housings 32 fixed to lower surface of the plate-shaped support base 2. Further, on both of two rounded guides 20 of the guiding-driving sub-assemblies 15, there are movably mounted trolley carriages 16 provided with plate-shaped angle-bar elements 34, vertical elements 35 of which are provided with cuboidal elements 36 having rounded recesses 37 with diameters adopted to diameters of rounded guides 20 on which they are fixed. On the other hand, horizontal elements 38 of angle-bar elements 34 are joined, by means of screws 39 and angled double-bent connecting members 40, with both ends of the plate-shaped working platform 17 having straight-through holes 42 on its surface and set in reciprocate motion by means of drive screws 21 driven by means of electric motors (not shown in drawings) powered by the controller 65. Further, the storage container unit 4 constitutes a rectangular frame 43, lower ends of outer surface of which are provided with rounded recesses 44 and the interior of which is formed by single-mode optical fibres 48 arranged symmetrically to each other and each having a light-transporting core 48' (made e.g. of glass) and a coating 48" impenetrable to light (made e.g. of a plastic). The optical fibres have diameter 1 pm and identical height equalling about 50% of height“W” of the frame, whereas upper ends of the optical fibres are permanently joined with light-converging lenses 49 with diameter equalling 1.1 of diameter of these optical fibres, while between rows of the optical fibres arranged alternately are conduits 50 distributing the light-curing material, e.g. a polymer resin, in the space between optical fibres, ends of said conduits being connected to a suitable conduit 51 supplying the resin and to a suitable conduit 5 returning, if necessary, the resin back to the reservoir 52 of the controlling-pumping unit 5 with the use of pump 53 driven by means of electric motor 54, whereas the conduits 50, along the whole of their lengths, are provided with straight-through holes 50' to facilitate faster and uniform distribution of the resin in the space between optical fibres and above upper surfaces of lenses up to a continuously topped-up level. Moreover, under lenses 49 of optical fibres 48 situated is a mesh 55 stabilising relative vertical position of these optical fibres, with side elements 56 of said mesh adhering to inner surface of frame 43 of the storage container 4, whereas lower ends of optical fibres 48 are straight-through fixed in a thin stiffening silicone layer 47, and lower surface of the frame 43, the silicone layer 47, and lower ends of optical fibres 48 are all flush with one another and rest of a source of light 45 disposed in a casing 45', said source of light being a liquid crystal display (LCD) which, together with the casing 45', forms a screen 45" powered with 24 V direct current via a power supply ribbon 46, under which there are: a rectangular frame-shaped insulating element 57 disposed on frame-shaped rectangular base 58 with comer cuboidal lower offsets 59 above which, in mounting seats 60, mounted are cylindrical pins 61 with vibration coils 62 fixed on the pins, whereas ends of these coils are situated in grooves 63 of the frame and are connected with electric conductors 64 of controller 65 controlling operation of the printer, while frame-shaped insulating element 57 adheres to lower surface of screen 45". The screen 45", situated under a silicone layer 47 and under lower ends of single-mode optical fibres 48 irradiating it, is joined, with the use of screws 66 and mounting holes 67 provided of both of the two shorter sides of casing 45' of the screen, with lower surface of rounded offsets 44 of rectangular frame 43 of the storage container unit 4.

Further, the frame-shaped rectangular base 58 and the rectangular frame-shaped insulating element 57 disposed on it are both joined together and fixed to bottom of the seat 9 of the plate-shaped support base 2 by means of screws 69 disposed in mounting holes 68.

The controlling-pumping unit 5 of the printer disposed on bottom 70 of the cabinet housing 1 comprises a pump 53 connected with an electric motor 54 and with reservoir 52 of a polymer light-curing resin, said reservoir being equipped with an intake port 71 coupled with controller 65 equipped with a computer program controlling operation of all working units of the printer and further provided with conduits 51 supplying the resin from the container 52 by the controller 65 to working portion of the storage container 4 and further equipped with conduits 5G returning, if necessary, the resin to the storage container 52.

The controller 65 is equipped with a general-purpose processor which, based on image of the printed product written in a 3D design program, controls operation of: motors driving drive screws 21 to set in motion carriages 16 together with the working platform 17, pumps 53, the power supply for the screen 45", and vibration coils 62.

The principle of operation of the printer consists in that after filling the reservoir 52 with a light-curing resin, the controller 65 powered from a 230 V power grid is started and appropriate buttons (not shown in figures) are pressed, as a result of which, the resin is pumped into working space of storage container 4 through supplying conduits 51 and distributing conduits 50, whereas the quantity of resin supplied to the storage container is controlled by the controller 65 up to such level that optical fibres 48 together with their lenses 49 remain always immersed; then, electric motors (not shown in drawings), controlled by the controller 65, set screws 21 in either clockwise or counter-clockwise rotational motion 21 setting thus in vertical motion the working platform 17 up to its contact with surface of a polymer light-curing resin disposed in working space of the storage container 4. Then, the controller 65 activates the source 45 of light which, after passing through a set of optical fibres 48, is focused by their lenses 49 as a result of which the first layer of resin with required thickness, for instance 100 pm, gets cured. Next, the working platform, as a result of reverse rotation of its driving screws 21, is lifted upwards also by 100 pm, and level of the resin is appropriately topped up, whereas the vibration coils 62, set in vibrational motion, enable faster inflow of resin up to above the level of lenses 49 of the optical fibres 48, an then the cycle of operations is repeated until the required overall dimensions of the product 72 designed in a computer 3D program are obtained.

It has been found that the use of optical fibres in the printer according to the invention allowed to irradiate the light-curing material with light with significantly higher intensity compared to this used in 3D printers known in the prior art which allowed to obtain larger thickness of cured layers of the printed product in a shorter time.

In the second variant of the printer for 3D printing shown in Figs. 15-17, the printer has the structure analogous to this described in the first version of its embodiment (Figs. 1-14), and the difference between the two variants consists only in that the storage container unit 4 lacks the frame-shaped rectangular insulating element 57 and the rectangular frame- shaped base 58 with vibration coils 62, while the screen 45" rests directly on bottom 9 of the plate-shaped support base 2. Further, optical fibres 48 protrude by length L = 3 mm below the lower surface of frame 43 and silicone layer 47 which are flush with one another the lower ends of optical fibres 48 rest directly on the source of light 45 which are light emitting diodes (LEDs).

In other variants of embodiment of the printer according to the invention, the following components were used:

- optical fibres 48 with diameter 10 pm, 200 pm, and 1 cm and length L of 10 cm, 50 cm, and 1000 cm;

- converging or diverging lenses 49 (selected depending on the used light-cured material) with diameter from 1 to 1.2 of the diameter of the optical fibres 48;

- a composite material as the light-curing material,

while the following were used a the source of light:

- a projector, UV lamps, light emitting diodes, laser diodes, laser, optical radiation sources, radioactive sources.

In all variants of embodiment of the printer, the principle of operation is analogous to this described above for the first variant.