Method and system for stereolithographic 3D print manufacturing

Abstract

Method for 3D print manufacturing, where print platform attaches to carrier of separate 3D printer, cover closes, printing program starts following printing parameters, printing material corresponding to printing parameters automatically fills resin tank, printing process corresponding to printing parameters automatically starts, cover opens after printing finishes, platform is removed from carrier using manipulator and attached to carrier of separate washing machine, airtight cover closes, printing parameters collected from printer are transferred, washing program starts, washing tub automatically fills with washing medium corresponding to printing parameters, print is automatically washed, washing medium vapors evacuate after washing finishes, cover opens, platform is removed from carrier using manipulator and attached to carrier of separate curing machine, cover closes, printing parameters collected from washing machine are transferred, curing program starts, print is automatically dried and irradiated with UV light corresponding to printing parameters, cover opens after curing finishes, and platform is removed using manipulator.

Description

Method and System for Stereolithographic 3D Print Manufacturing

[0001] The invention relates to the field of additive manufacturing of three-dimensional objects using layers of liquid which are selectively solidified, specifically additive layering by stereolithographic 3D printing using light-cured resins, and to the field of auxiliary operations of additive manufacturing, specifically cleaning of prints and hardening of prints.

[0002] Stereolithographic 3D printing technologies allow photopolymer resins to be processed into complex 3D objects. Printing is carried out layer by layer in horizontal two-dimensional sections of the object, where individual layers are selectively exposed to light according to pre-prepared data. To polymerize the material in individual layers, radiation of a specific wavelength is used, to which the photoinitiation system, which is part of the resin, must be selective. This concept is generally known, for example, from documents WO2019094431 or WO2018232175. The resin is placed in a resin tank equipped with a bottom that transmits radiation of this wavelength. The bottom of the resin tank is made of a polymer film, usually based on fluorinated ethylene-propylene (FEP) copolymer. Radiation penetrating through the film at the points to be printed triggers the polymerization of the resin and creates a cured layer. The polymerizing areas are exposed to ultraviolet (UV) radiation emitted either by a scanning laser or by a full-area projection of the print pattern into the resin tank through a mask, typically in the form of a liquid crystal display (LCD) backlit by a UV light-emitting diode (LED) array. After the exposure of one layer is completed, the emerging print object is moved in the z-axis direction, while the newly formed layer of the object is separated from the bottom of the resin tank. This process is repeated until a complete 3D print is created.

[0003] However, the polymerization process initiated by LCD-mediated radiation is characterized by an insufficient efficiency, and the prints are therefore imperfect in terms of their mechanical properties. To achieve the desired properties, the polymerization process is completed by an additional intensive irradiation, called curing or hardening. Devices in the form of curing chambers are known from the prior art, for example from the document US11155032B2. In such chambers, the print is illuminated with the desired wavelength from multiple sides, typically by a UV LED assembly. However, due to the high viscosity of the monomer resin, the 3D printed material is significantly contaminated by resin residues adhering to the surface of the print. As such, the print would be degraded by additional polymerization of these residues if transferred directly from the 3D printer to the curing chamber. Therefore, the print is washed with a cleaning medium, such as isopropyl alcohol (IPA) or water with surfactants to remove the residues. The washing can be done manually or using dedicated washing devices. Such devices are known from the prior art, for example from documents US11358336B2 or US2023278288A1.

[0004] Automation of all three described processes is known from the prior art. For example, document KR102078575B1 describes a fully automated device consisting of a rotating arm with a printing platform and three chambers for printing, washing, and curing, respectively. The chambers have open tops and are located around the rotating arm. Document US11097467B2 describes a fully automated device consisting of a static arm with a printing platform and three chambers for printing, washing, and curing, respectively. The chambers are rotatable or movable relative to the arm and the device can additionally comprise areas for loading and unloading the printing platform. Such devices are inherently characterized by significant space requirements considering the relatively small size of prints they can produce, as for a print with maximum dimensions in decimeters, these devices require a space at least the size of a regular room. Furthermore, due to the fundamental necessity of using open chambers containing hazardous chemicals and UV radiation sources, it is necessary to enclose the device in a gas- and light-insulated room to maintain the safety of the operator or to equip the operator with safety equipment in the form of a full-body protection against UV radiation and a breathing apparatus. The described devices are therefore suitable exclusively for large-scale industrial operations.

[0005] A more compact solution is also known from the prior art, specifically from document KR102608819B1. However, to achieve such a compact form factor, the system is highly integrated allowing only for a fixed combination of one 3D printer, one washing station, and one curing station. Therefore, taking into account that printing process is inherently the longest-lasting compared to washing and curing, even in a combination of more such systems together, each washing station has to wait for printing process to finish and each curing station has to wait for printing and washing processes to finish.

[0006] According to solutions known from the prior art, it is therefore either possible to create a 3D print using parameters tailored to the given print, but at the cost of an inefficient industrial arrangement, where each 3D printer has a dedicated washing machine and a dedicated curing machine, or to create a 3D print with a more efficient industrial arrangement, such as using mutually unconnected devices incapable of mutual transmission or sharing of information, but at the cost of lower print quality due to the use of generic processing parameters. The technical problem is therefore the lack of solutions known from the prior art combining the advantages of both approaches and eliminating their shortcomings.

[0007] Goal of the present invention is to introduce a 3D printing method characterized by a high degree of automation while being significantly adaptable to specific requirements of a particular print, and to introduce a compact device for carrying out such method having space requirements comparable to non-automated systems known from the prior art while ensuring maximum user protection, while allowing to freely configure the number of individual devices in an industrial production.

[0008] The present invention is a method for stereolithographic 3D print manufacturing, where a print platform is attached to a carrier of a separate 3D printer, a 3D printer cover separating a printing space of the 3D printer from its external environment is closed, a printing program is started according to uploaded printing data with printing parameters, an amount of UV-curable printing material corresponding to the printing parameters is automatically filled into a resin tank, and a 3D printing process corresponding to the printing parameters is automatically started. After the 3D printing process is finished, the 3D printer cover is opened, the print platform is removed from the 3D printer carrier using a manipulator and is attached to a carrier of a separate washing machine, a washing machine cover airtightly separating a washing space of the washing machine from its external environment is closed, printing parameters collected from the 3D printer are transferred, a washing program is started, a washing machine tub is automatically filled with a washing medium corresponding to the printing parameters, and the print is automatically washed. After the washing is finished, washing medium vapors are evacuated out of the washing space of the washing machine, the washing machine cover is opened, the print platform is removed from the washing machine carrier using the manipulator and is attached to a carrier of a separate curing machine, a curing machine cover separating a curing space of the curing machine from its external environment is closed, printing parameters collected from the washing machine are transferred, a curing program is started, the print is automatically being dried, and the print is automatically being irradiated with UV light corresponding to the printing parameters. After the curing is finished, the curing machine cover is opened and the print platform is removed from the curing machine carrier using the manipulator.

[0009] Printing parameters can be transferred manually between 3D printing, washing, and curing, by reading information from a display after completing one step and entering the information before starting a next step. Advantageously, printing parameters can be transferred automatically via rewritable NFC (Near Field Communication) tags and NFC modules adapted to write and edit data stored on NFC tags. Main NFC modules are located on print platform carriers in the 3D printer, the washing machine, and the curing machine, respectively, and a main rewritable NFC tag is located on the print platform, so that it communicates with the main NFC modules. Additional NFC modules are located on a holder for a printing material canister and on a mount for the resin tank, and additional NFC tags are located on the printing material canister and on the resin tank. The main NFC modules read from and write on the main NFC tag, in particular, the following print parameters: information about the required print dimensions, type of printing material, parameters of the finished 3D printing process, print size, used printing material, parameters of the finished washing process, used washing media, parameters of the finished drying and curing process. Additional NFC modules read to and write from the additional NFC tags information about a type of printing material in a specific canister and information about previous 3D printing processes made using a specific resin tank, including positions of prints on the print platform.

[0010] The printing parameters and their transfer between the individual steps of 3D print manufacturing are essential for optimizing and automating the 3D printing, washing, and curing processes. Based on the data, compatibility of the printing material in the canister with the required type of printing material is automatically verified, position of the print on the print platform is automatically set with respect to parts of the bottom of the resin tank that can be worn out by repeated printing, provided amount of the printing material is automatically set, printing space of the 3D printer is automatically heated to a temperature corresponding to the printing material used, time and intensity of exposure during printing are automatically set, position of the print in the washing machine tub is automatically determined or set, type and amount of washing medium are automatically set, temperature and flow rate of hot air for drying are automatically set, wavelength and intensity of exposure for curing are automatically set, curing space of the curing machine is automatically heated for prints made from printing materials requiring additional heat during curing.

[0011] All the above-mentioned printing parameters can be collected and archived at the end of the 3D print manufacturing for purposes of a post-process reporting, for example in cases of 3D prints made from biocompatible printing materials used in a clinical medical practice.

[0012] Furthermore, the present invention is a system for carrying out the method for 3D print manufacturing, which consists of a print platform, a 3D printer, a washing machine, a curing machine, and a manipulator, with the 3D printer, the washing machine, and the curing machine being each a separate device. The print platform is advantageously equipped with a rewritable NFC tag. The 3D printer is provided with at least one printing material holder advantageously equipped with an NFC module and at least one printing material canister stored therein, which is equipped with a two-way, two-channel printing material duct and the printing material duct is connected to the canister and a printing material dispenser. The 3D printer is further provided with a carrier for attaching the print platform, the carrier being advantageously equipped with an NFC module, a resin tank capable of two-way tilting advantageously equipped with a rewritable NFC tag, a resin tank mount advantageously equipped with an NFC module, and a UV-blocking cover. The washing machine is provided with a carrier for attaching the print platform, the carrier being advantageously equipped with an NFC module, a cover, a seal around an entrance to a washing space of the washing machine, a tub, and at least one washing medium reservoir. The curing machine is provided with a carrier for attaching the print platform, the carrier being advantageously equipped with an NFC module, a UV-blocking cover, and a source of UV radiation, advantageously in the form of UV LEDs. The manipulator is provided with a mechanism for securing the print platform, a drip tray to prevent workspace contamination, and a handle to prevent the 3D printer user from coming into contact with the printing material or washing medium.

[0013] The present invention achieves both intended advantages, as it is possible to freely configure the number of individual devices in industrial production and at the same time create a print using printing parameters specifically adapted to a given 3D print, and thus overcomes technical problems arising from the prior art.Fig.1

[0014] depicts a compact assembly of a 3D printer with an open cover, a washing machine, and a curing machine together with a 3D printer user holding a manipulator.Example 1

[0015] Example 1 describes preparatory steps for carrying out a 3D printing process according to the present invention.

[0016] A canister with a printing material in the form of a UV-curable resin is inserted into a printing material holder of a 3D printer and a cap equipped with two tubes is attached to the mouth of the canister, one tube for pumping the printing material out of the canister and the other tube for pumping it back into the canister. The printing material holder is then slid along specially adapted rails into the space of the 3D printer reserved for the printing material holder, thereby achieving an effective separation of the printing material from spaces where a user of the 3D printer moves.

[0017] If the canister is not equipped with an NFC tag containing information about the type of printing material, this information is entered into the 3D printer manually. If the canister is equipped with an NFC tag containing information about the type of printing material, the NFC module of the printing material holder of the 3D printer logs this information automatically.

[0018] A resin tank is placed in a resin tank mount. If the resin tank is equipped with an NFC tag containing information about previous prints including positions of the prints on a print platform, an NFC module of the resin tank mount logs this information automatically.Example 2

[0019] Example 2 describes a method of 3D print manufacturing according to the present invention with a manual transfer of information.

[0020] A print platform is attached to a carrier of a separate 3D printer and a cover of the 3D printer is closed. The carrier is movable in a z-axis and the cover is made of extruded plexiglass that absorbs UV light and it separates a printing space of the 3D printer from its external environment. Afterwards, a printing program is started according to uploaded printing data containing printing parameters together with information about required print dimensions and a required type of a printing material. During a run of the printing program, first, a printing material dispenser in the form of a tiltable tap automatically fills a resin tank with an amount of printing material corresponding to the printing parameters, then the printing space of the 3D printer is automatically heated to a temperature ensuring optimal printing results for the printing material used, and a 3D printing process using a stereolithography method is automatically started with the printing parameters automatically set to values ​​ensuring optimal printing results for the printing material used. Surface level of the printing material is automatically continuously monitored throughout the 3D printing process by a sensor and the printing material is automatically replenished in case a shortage is detected. After the 3D printing process is finished, any unsued printing material is automatically pumped out by the printing material dispenser through a filter back to a canister in a printing material holder and a complete removal of the printing material is achieved by an automatic tilting of the resin tank. Afterwards, the 3D printer cover is opened and the print platform is removed from the 3D printer carrier using a manipulator equipped with a safety pin to secure the print platform, a drip tray to prevent contamination of a workspace with printing material when transferring the print platform with a print, and a handle. The print platform is then attached to a carrier of a separate washing machine and a cover of the washing machine is closed. The carrier is movable in a z-axis and the cover is made of polycarbonate and it airtightly separates a washing space of the washing machine, which is also a glove box, from its external environment. Then, information about the print size and used printing material, collected from a display of the 3D printer, is entered using a display of the washing machine, and a washing program is started. During a run of the washing program, first, the carrier of the washing machine automatically descends to a lowest possible position, so that the lowest part of the print is near a bottom of a tub of the washing machine to minimize the amount of a washing medium used. Then, the tub is automatically filled with the washing medium, which is automatically selected to achieve an optimal washing of the print based on the used printing material, in an amount such that the highest-placed part of the print is just below the surface of the washing medium, and the print is automatically washed by a swirling movement of the washing medium. After the washing process is finished, the washing medium is automatically pumped out and the carrier of the washing machine automatically moves to its highest position. To achieve optimal cleanliness of any complex shapes of the print, the print undergoes a final manual cleaning with the washing medium inside the washing space of the washing machine using gloves and a pressure hose with a nozzle. After the washing is complete, vapors of the washing medium are automatically evacuated out of the washing space and pumped through a carbon filter for their neutralization, the washing machine cover is opened, and the print platform is removed from the washing machine carrier using the manipulator. The print platform is then attached to a carrier of a separate curing machine and a cover of the curing machine is closed. The carrier is movable in a z-axis, the cover is made of extruded plexiglass that absorbs UV light and it separates a curing space of the curing machine from its external environment, and inner walls of the curing space are made of a reflective material. Then, information about the print size, used printing material, and used washing medium, collected from a display of the washing machine, is entered using a display of the curing machine, and a curing program is started. During a run of the curing program, the print automatically evenly rotates along the z-axis, hot air is automatically blown into the curing space, with temperature and flow rate of the hot air being automatically set based on the used washing medium to achieve optimal drying, and the print is automatically irradiated with UV LEDs, with irradiation parameters in the form of wavelength and intensity being automatically set to values ​​ensuring optimal curing results for the used printing material. After the curing process is finished, the curing machine cover is opened and the print platform is removed from the curing machine carrier using the manipulator.Example 3

[0021] Example 3 describes a method of 3D print manufacturing according to the present invention with an automated transfer of information.

[0022] A print platform equipped with a rewritable NFC tag is attached to a carrier of a separate 3D printer and a cover of the 3D printer is closed. The carrier is movable in a z-axis and equipped with an NFC module, the cover is made of extruded plexiglass that absorbs UV light and it separates a printing space of the 3D printer from its external environment. Based on uploaded printing data containing printing parameters together with information about required print dimensions and a required type of a printing material, a compatibility of the printing material present in a canister in a printing material holder is verified, and information about previous prints stored on an NFC tag of a resin tank is used to automatically set an optimal position of a print on the print platform. Afterwards, a printing program is started. During a run of the printing program, first, a printing material dispenser in the form of a tiltable tap automatically fills the resin tank with an amount of printing material corresponding to the printing parameters, then the printing space of the 3D printer is automatically heated to a temperature ensuring optimal printing results for the printing material used, and a 3D printing process using a stereolithography method is automatically started with the printing parameters automatically set to values ​​ensuring optimal printing results for the printing material used. Surface level of the printing material is automatically continuously monitored throughout the 3D printing process by a sensor and the printing material is automatically replenished in case a shortage is detected. After the 3D printing process is finished, any unsued printing material is automatically pumped out by the printing material dispenser through a filter back to the canister in the printing material holder and a complete removal of the printing material is achieved by an automatic tilting of the resin tank. NFC module of a resin tank mount writes information about the position of the print on the print platform to the NFC tag of the resin tank. The NFC module of the 3D printer carrier writes information about the parameters of the print, the position of the print on the print platform, the print size, and used printing material to the NFC tag of the print platform. Afterwards, the 3D printer cover is opened and the print platform is removed from the 3D printer carrier using a manipulator equipped with a safety pin to secure the print platform, a drip tray to prevent contamination of a workspace with printing material when transferring the print platform with a print, and a handle. The print platform is then attached to a carrier of a separate washing machine and a cover of the washing machine is closed. The carrier is movable in a z-axis and equipped with an NFC module, the cover is made of polycarbonate and it airtightly separates a washing space of the washing machine, which is also a glove box, from its external environment. Then, the NFC module of the washing machine carrier reads information about the print size and used printing material from the NFC tag of the print platform and a washing program is started. During a run of the washing program, first, the carrier of the washing machine automatically descends to a lowest possible position, so that the lowest part of the print is near a bottom of a tub of the washing machine to minimize the amount of a washing medium used. Then, the tub is automatically filled with the washing medium, which is automatically selected to achieve an optimal washing of the print based on the used printing material, in an amount such that the highest-placed part of the print is just below the surface of the washing medium, and the print is automatically washed by a swirling movement of the washing medium. After the washing process is finished, the washing medium is automatically pumped out and the carrier of the washing machine automatically moves to its highest position. To achieve optimal cleanliness of any complex shapes of the print, the print undergoes a final manual cleaning with the washing medium inside the washing space of the washing machine using gloves and a pressure hose with a nozzle. After the washing is complete, vapors of the washing medium are automatically evacuated out of the washing space and pumped through a carbon filter for their neutralization, the NFC module of the washing machine carrier adds information about parameters of the finished washing and used washing medium to the NFC tag of the print platform, the washing machine cover is opened, and the print platform is removed from the washing machine carrier using the manipulator. The print platform is then attached to a carrier of a separate curing machine and a cover of the curing machine is closed. The carrier is movable in a z-axis and equipped with an NFC module, the cover is made of extruded plexiglass that absorbs UV light and it separates a curing space of the curing machine from its external environment, and inner walls of the curing space are made of a reflective material. Then, the NFC module of the curing machine carrier reads information about the print size, used printing material, and used washing medium from the NFC tag of the print platform and a curing program is started. During a run of the curing program, the print automatically evenly rotates along the z-axis, hot air is automatically blown into the curing space, with temperature and flow rate of the hot air being automatically set based on the used washing medium to achieve optimal drying, and the print is automatically irradiated with UV LEDs, with irradiation parameters in the form of wavelength and intensity being automatically set to values ​​ensuring optimal curing results for the used printing material. After the curing process is finished, the NFC module of the curing machine carrier adds information about parameters of the finished drying and curing to the NFC tag of the print platform, the curing machine cover is opened, and the print platform is removed from the curing machine carrier using the manipulator.Example 4

[0023] Example 4 describes a system for carrying out a method for 3D print manufacturing according to the present invention.

[0024] System consists of a print platform, a 3D printer, a washing machine, a curing machine, and a manipulator.

[0025] The print platform is equipped with a rewritable NFC tag.

[0026] The 3D printer is provided with a printing material holder equipped with an NFC module and a printing material canister stored therein. The canister is equipped with a two-way, two-channel printing material duct and the printing material duct consists of two tubes connected to a cap of the canister and to a printing material dispenser in the form of a tiltable tap. The printing material duct is further equipped with a filter situated in the tube leading from the dispenser to the canister. The 3D printer is further provided with a carrier for attaching the print platform, the carrier being equipped with an NFC module, a resin tank capable of two-way tilting equipped with a rewritable NFC tag, a resin tank mount equipped with an NFC module, a sensor for monitoring surface level of a printing material, and a UV-blocking cover made of extruded plexiglass.

[0027] The washing machine is provided with a carrier for attaching the print platform, the carrier being equipped with an NFC module, a cover made of polycarbonate, a rubber seal around an entrance to a washing space of the washing machine, two gloves for manipulation with items in the airtight washing space, a tub, two washing medium reservoirs, a pressure hose with a nozzle, and a ventilation system equipped with a carbon filter.

[0028] The curing machine is provided with a carrier for attaching the print platform, the carrier being equipped with an NFC module, a UV-blocking cover made of extruded plexiglass, inner walls with a reflective surface finish, an assembly of UV LED strips with an emission wavelength of 405 nm, an assembly of UV LED strips with an emission wavelength of 385 nm, and an assembly of UV LED strips with an emission wavelength of 365 nm, with the UV LED strip assemblies situated in corners inside a curing space of the curing machine.

[0029] The manipulator is provided with a safety pin to secure the print platform, a drip tray to prevent workspace contamination, and a handle for a safe manipulation.

[0030] Method and system for 3D print manufacturing are industrially applicable in stereolithographic 3D printing.

Claims

Method for stereolithographic 3D print manufacturing,characterized in thata print platform is attached to a carrier of a separate 3D printer, a 3D printer cover separating a printing space of the 3D printer from its external environment is closed, a printing program is started according to uploaded printing data with printing parameters, an amount of UV-curable printing material corresponding to the printing parameters is automatically filled into a resin tank, and a 3D printing process corresponding to the printing parameters is automatically started, after the 3D printing process is finished, the 3D printer cover is opened, the print platform is removed from the carrier of the 3D printer using a manipulator, the print platform is attached to a carrier of a separate washing machine, a washing machine cover airtightly separating a washing space of the washing machine from its external environment is closed, printing parameters collected from the 3D printer are transferred, a washing program is started, a washing machine tub is automatically filled with a washing medium corresponding to the printing parameters, the print is automatically washed, after the washing is finished, washing medium vapors are evacuated out of the washing space of the washing machine, the washing machine cover is opened, the print platform is removed from the carrier of the washing machine using the manipulator, the print platform is attached to a carrier of a separate curing machine, a curing machine cover separating a curing space of the curing machine from its external environment is closed, printing parameters collected from the washing machine are transferred, a curing program is started, the print is automatically dried, and the print is automatically irradiated with UV light corresponding to the printing parameters, after the curing is finished, the curing machine cover is opened and the print platform is removed from the carrier of the curing machine using the manipulator.System for carrying out the method for stereolithographic 3D print manufacturing according to claim 1,characterized in thatit consists of a print platform, a 3D printer, a washing machine, a curing machine, and a manipulator, with the 3D printer, the washing machine, and the curing machine being each a separate device, the 3D printer is provided with at least one printing material holder and at least one UV-curable printing material canister stored in the printing material holder, each printing material canister is equipped with a two-way, two-channel printing material duct and the printing material duct is connected to the printing material canister and a printing material dispenser, the 3D printer is further provided with a carrier for attaching the print platform, a resin tank capable of two-way tilting, a resin tank mount, and a UV-blocking cover, the washing machine is provided with a carrier for attaching the print platform, a cover, a seal around an entrance to a washing space of the washing machine, a tub, and at least one washing medium reservoir, the curing machine is provided with a carrier for attaching the print platform, a UV-blocking cover, and a source of UV radiation.System according to claim 2,characterized in thatthe manipulator is provided with a mechanism for securing the print platform, a drip tray to prevent workspace contamination, and a handle to prevent the 3D printer user from coming into contact with a printing material or a washing medium.System according to claim 2,characterized in thatthe carrier of the 3D printer, the carrier of the washing machine, and the carrier of the curing machine are each equipped with an NFC module, and the print platform is equipped with an NFC tag.System according to claim 4,characterized in thateach printing material holder and the resin tank mount are each equipped with an NFC module, and each printing material canister and the resin tank are each equipped with an NFC tag.

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